Waist harnesses are a tricky one to get right, just trying one on on dry land doesnt give you a particularly good idea of what it'll be like after a kite has been pulling it for a few hours in various directions.
Are you making the transition from a seat harness? or are you used to using a waist already?
You'll find that you'll actually need to change the way you ride with a waist, as it is uncomfortable keeping the kite above you, and you also have the possibility of it riding up when you wipeout, or gradually during the course of your session - this can be very uncomfortable.
Besides that, make sure you get the right size. You can easily get away with the wrong sized seat harness, but not at all with a waist. If you can borrow someone elses for an hour that would be ideal.
As for recommendations, I use the dakine pyro, which is pretty decent, and considerably better than the tabu imo. The north riders also seem happy with theirs, so that could be a good option too. Ocean Rodeo do a nice convertible one, which can be used as both seat and waist, with detachable leg straps, I've seen a few people using those.
Hope this helps a little, i converted from seat->waist at the end of last year, and although it was difficult and uncomfortable at first, my seat harnesses are now firmly confined to the cupboard
