Now that I've begun to work with the X61, I can make a few comments about it, in the hopes that these will be useful to others considering a new tablet pc.
First, keep in mind that my previous tablet was a Toshiba Tecra M4, a very different animal. Both of these are machines that garnered enthusiastic reviews and that are generally much liked by their users, but some of what a person will like about one will be unavailable on the other.
The M4 is more of a desktop-replacement model: it's big and relatively heavy. The advantage of this is that there's a good-sized screen and that it has a bay where you can swap among CD/DVD drive, second hard drive, and a second battery.
I really loved having a second hard drive right there with me all the time. What I'm realizing with the X61 is that although I bought a primary hard drive that is larger than the two others combined, I tend to feel as though the programs and user files are all mixed together. In other words, ideally the user installs all the programs before introducing any user files, and this keeps things somewhat separate on the disk. But of course in real life it never works that way. You install a few programs, you copy over your documents and work on them, you install another program or two or an update, etc. Let's just say that when I tried running the defragger a day or two into the process of setting up the X61, the hard drive was already astonishingly fragmented. On the M4, with the two hard drives, most of the user files were on the second hard drive, and there was rarely much fragmentation there. Now, it's true I could partition the X61's hard drive, but past experience in partitioning drives suggests that I never allot enough space to something. It is hard to judge expansion needs for either programs or user files. Still, maybe partioning half-and-half would be OK.
The X61, being a super-light model, doesn't come with a CD/DVD drive, and the screen is small. One either hooks up an external CD/DVD drive or buys the Unibase (dock) AND a CD/DVD drive. I opted, perhaps foolishly, for the dock on the theory that it should give me more options. You can travel with the dock, in which case the whole thing weighs somewhere around the same amount as the M4. For instance, just as with the M4, you can swap out the CD/DVD for a second hard drive or battery. I thought that seemed more appealing than plugging in a second hard drive to a USB port and trying to travel. Actually, what I think I will do is put my archival TIF files onto a second hard drive. I don't need to use them very often as the JPG versions are what I use for presentations and reference.
So... on the CD/DVD and second hard drive/battery issue, neither machine is better than the other, just different. It is nice to be able to leave the weight behind.
On the screen issue, however, I find that I really miss the larger viewing area. OK, it was the screen that was failing on the M4, but that's beside the point. I don't think I would really recommend such a small screen to another art historian, but then again it depends on how a person works. I like to have a whole page of a document nicely visible in portrait mode. For instance, someone's dissertation in PDF. Large type is always nice. And when working in Photoshop, I like to have the image nice and large. One thing I do in Photoshop is add IPTC data about the images--everything I can find about about the medium, dimensions, owner, source of scan, etc. Often I've been in a hurry making the initial TIF files and am doing the IPTC data later, working from the caption that was scanned along with the work of art. There is not enough screen real estate on the Lenovo to see both the IPTC data entry screen and the scanned info, so I constantly have to move the IPTC window around to see one or another bit of the scan. I also notice that in OneNote, which I've begun to try using for lecture notes and such, I find the writing area small. Others may not find this as important, obviously. Still, I think my vote for future lightweight development would be for a bigger screen on a fairly thin laptop.
This is also significant for the keyboard. I had never understood what people were complaining about when they said laptop keyboards were too small; I assumed this was because I have small hands that find laptop keyboards comfortable. This is the first keyboard that has struck me as cramped. It's not the keys themselves, which look normally sized. I assume they are closer together. This, however, is something I expect I will get used to. For that matter, on a tablet, many users primarily use pen input, so this would be insignificant. I mainly use the keyboard, although I love having the tablet feature.
Another keyboard matter is the placement of keys. Every manufacturer, for reasons unknown to me, likes to move certain keys into its own favorite locations. On the M4, for example, I had to get used to having the Windows key up at the top of the keyboard rather than near the Shift key. Initially I hated that, but now I'm used to it and have to get used to having it in the more usual location.
I don't recall where other keyboards I've used put the Fn key (which I almost never use), but on the X61 it's right where I expect the Ctrl to be. I'm constantly hitting Fn instead of Ctrl and am learning not to touch-type Ctrl but to raise my hand and look for it.
Another thing I'm disliking on the X61 keyboard is that the Delete, End, Home, PageUp and PageDown keys are way at the top. I'm glad Lenovo stuck Insert there, since on the M4 I often accidentally hit it (another key I don't normally use) instead of Alt, but on the M4 I was accustomed to being able to touch-type Delete, End, Home, PageUp, and PageDown, and on the X61 they are really out of reach. Does Lenovo really think a person doesn't want easy access to Delete? I think all of us surely use Delete quite a bit, and I myself use the others a lot. Escape, too, is way up there, but that's a little less problematic. I use the Escape key, but apparently I always hunted for it rather than touch-typing.
A very odd thing about the keyboard is that the F keys and number keys seem to be farther to the left than on other keyboards. I use these keys a certain amount and this means I am often typing the wrong one. I use F5 and F6 a lot in Nota Bene, and when typing in Czech I need to use the number keys for the Czech characters (or, indeed, when using the French keyboard I also need to use those keys, although I try to avoid using the French keyboard since it has some weird key placements for A, Q, and M).
The X61 uses a pointer rather than a touch-pad. In theory I have no real preference; both do the job, and are vast improvements on the mouse, which is an anti-ergonomic abomination. I do find, however, that the pointer is slower to operate than the touch-pad, and requires much more finger effort. This bugs me much more than I would have expected.
Lenovo computers evidently come with a lot of security features, which I can imagine many users find a wonderful enhancement. Initially, I thought these might be a plus. I don't, however, store a whole lot of things that I would be worried about thieves accessing. No doubt there are a few things, but the average thief is looking for a laptop, not the data. I quickly found that I really, really hate having to log on to my own computer. I do not want my entire life password-protected. I have not figured out how to disable some of these protections, so even though I got rid of passwords, the computer still asks for them. I'm reminded of all those incidents at conferences where we're using someone's password-protected laptop and after a break it goes to sleep, wants the user's password, and no one even knows whose laptop it is so the session goes on hold while someone tries to find out whose laptop we're using. Other users will have a very different reaction to the security features, of course.
I've been using the X61 for nearly three weeks now, so I may be as accustomed to it as I'll get. We'll see.
On the whole, I think the design of the M4 was better suited to my personal needs, but the X61 is nonetheless an impressive machine and for the most part merely different.