Measuring several factory Colt slide stops, I find they are .205" wide at the widest point, and that the shelf sticks out .118". With the Wilsons I have, they are .220" wide at the widest point, and the shelf again sticks out .118". For me, however, the Wilson feels like it sticks out less, and it's harder to hit for me on all my guns. I only use it because it's a strong part, and I have yet to hear of one breaking. The problem to me is that the pad is lower. I figure it might take a little time to get used to, but eventually I'll develop the muscle memory I need on these. You might look at the one Nighthawk Custom makes as an alternative, though I don't know if they stick out further.
As a side note, I put a Wislon in today and it will not lock back on empty Wilson mags, and all my mags have new or newr springs. Any other slide stop I have, be it Colt, Springfield, EGW, Ed Brown, etc., will lock it back. It's the first "bad" part I've gotten from Wilson in 10 years.