The TU-2 was my favorite before I found the VS-1. From my point of view, here's why the VS-1 is better:
When I tuned with the TU-2, I'd get the guitar in tune (according to the tuner) and then notice after a song of two (sometimes less) that the intonation wasn't quite right. I always blamed it on the guitar - warming up, strings slipping or binding, etc. and just treated it as fact of life... Of course, the TU-2 made it easy to touch up the tuning because of that nifty little footswitch, but it was never exactly right no matter how often I touched up the tuning.
Now here's the important bit. The tuning wasn't out according to the TU-2, but it was still out far enough (maybe a couple of cents) that I could hear the problem with certain chords at certain positions on the neck.
Then I got the VS-1. Now I can tune at the beginning of the set and the intonation holds through the entire set. No retuning, no tweaking... I don't even bother to have the VS-1 in my signal chain. I set it on top of the amp and just switch the plug from the amp to the tuner and back before the set starts. It's amazing. I haven't changed anything else - same guitars, same brand of strings, same wrap around the post, same setup, same playing style. The VS-1 is about 10x more accurate than the TU-2, and my instrument sounds great when the VS-1 says that it is in tune.
The lesson I learned: when my guitar is really in tune, there's no need to keep fixing the tuning. And the VS-1 is the only tuner I've tried that tunes accurately, every time.