I'm at a stage where I'm really starting to appreciate doing kata very slowly. My Sensei has really been making a point that it is much easier to see mistakes, get good form, etc if you practice slowly.
In my case, I usually do a couple of kata very slow. Looking for "perfection", then I do a couple normal speed, working on power, speed and rythm. (I've given up on grace, as I'm like an elephant on ice!
Actually, it's coming slowly!! )
As for Tai-chi, the first time I heard about it was about 12 years ago. I've crossed paths with a few few folks who study it. It's a very intresting style, and I've wondered at times if it would be a good complement to Uechi training. My only "issue" has been figuring out how to know who is well versed, and who is simply teaching the stuff they learned a year or two ago. Well, that and not having enough time for all of the other things I need to do.