Airforce -
I am currently using the Grip Loc thumb system and love it. I was having thumb issues and I really dislike using tape. My pro shop guy recommended the Grip Loc and I really like it. So far I have gotten away with drilling only two slugs, but I can usually get a good feel in the thumb using one of them.
My pro shop guys tells me that he has seen some trouble with the other systems breaking, etc., but has had really good realiability with the Grip Loc. He himself uses the system, is a great bowler and I trust his judgement. The grips themselves are stable and easy to change. From what I know, they are also easier to install (maybe that's why my guy likes them!).
I'd give it a shot.
299 - Roto SD-73 Classic
299 - Elite Black Label
298 - Roto SD-73
297 - Brunswick C 3.5
290 - Roto Rogue Cell