Tested this over at Tim's house yesterday, feels great.
I am seriously considering picking up a TE just to throw one of these one there (I only have an SE and a TvC stick, no TE somehow).
Markman did some good work here.
As for the hand positioning, there's a guy here in Ohio (and a few others I've seen) who play on arcade with their right hand on the attack/block buttons, and uses his LEFT thumb for run.
There's another one who moves his whole hand and taps every single button with his first two fingers (crazy).
I don't think any other game comes close to UMK3 and having the variety of ways people will play on the same layout. It's always amazed me. Having this new option is definitely a good thing.