I looked at the LifeDrive but decided on the T|X for a few reasons...
First, the price. LifeDrive is around $600 (CDN), compared to $400 (CDN) for the T|X. Second, the battery life of the T|X is (reportedly) better, due to no hard drive (and a *slightly* slower processor 312 Mhz vs. 416 Mhz - but it shouldn't make that noticable a difference).
Third, I just didn't see a need for 4 gigs of built-in memory for myself. I have 92.1M of the 114.8M of the T|X's flash memory remaining unused for the moment. This is with several books, and the complete PHP docs (4 megs!) all in internal flash. Fourth, the LifeDrive's issues... Such as loading time, stability (supposedly fixed in the ROM update), and similar things.
Fifth, I suppose, is that I prefer the T|X's form, compared to the bulkier LifeDrive. Reminicient of some of Palm's old models (Vx, some of the m-series, etc.), but with nice things like Wifi.
The only major 'problem' I have with the T|X is a slight screen-whine that's been, from some research, a problem on several recent Palm models. It's hardly noticable, however. In fact the only time I heard it when I didn't try to was when reading something in Blazer, with my T|X propped up (landscape) against something on a table, while eating a bowl of cereal. (Yes, certainly an odd situation!) Other than that, I've only heard it when I put my ear purposely next to the screen, trying to hear if it had that whine.