I've had a Super Stroke putter grip for nearly a year and have used it on and off in actual play so I'll try to give my impressions and perhaps some advice to help with the weight/balance issue.
First off - it certainly does help quiet over-active wrists... which is why Choi and a few others are using it. I found that when I play really quick greens it was more effective than a regular sized grip and helped me maintain a smooth flow to the putting stroke.
Secondly, the weight/balance issue is something worth experimenting with by using lead tape on either the putter head or else the shaft just below the grip. If you've read anything about the Torpedo Golf putter that P. Harrington used to win a European Tour event last year right before the British Open then you'll know what I'm talking about. Basically it's a brass insert in the putter shaft just below the grip to "harmonize" the shaft. I used lead tape (two or three strips about 8" long) to achieve pretty much the same effect and am using that on all my putters (don't ask!) now and I feel strongly that something like this will be one of the next "big things" in putter technology very soon.
For me it helped re-balance the putter with the Super Stroke grip and made the whole putter feel more comfortable while putting. Highly recommended!
The length is another factor with the Super Stroke that might take some experimenting as well - it comes with a plastic tube that fits into the end of your putter shaft and you can either add or cut off sections to come up with the proper feeling length. Again, it's going to take some messing around because to use the Super Stroke in USGA competition you have to glue the screws into the shaft to make it permanent, which is something I wasn't ready to do right now. I fiddle with clubs, shafts and grips way, way too much for my own good but it keeps things fresh and exciting for me and keeps me from buying too many clubs to experiment with - I don't consider the ten lob wedges I have in my golf shop too many, by the way!
hope this helps a bit -
Scott