I was going to start a thread about this, but seeing as you haven't gotten any responses in 3 1/2 years, there's probably no use.
Today I bought an oversized grip for my putter (WinnProX 1.18 with a flat side). It's not as big as the SuperStroke 5.0, but I'm hoping it will still help the part of my game that seems to be costing far too many strokes which are short putts.
@colin007, did you end up finding the grip you were looking for? Does anyone else use an oversized grip? If so, why did you switch and does it seem to help?