Depends on You
I also have always used a suicide grip for squats because when the weight gets heavy, two things seem to happen to me.
1. The weight kills the area between my index finger and thumb, I guess you would call that the thumb joint? Like some pretty heavy pain that subsides quickly but is not comfortable.
2. It also forces my wrists into a pretty awkward angle that I feel isn't very natural. It feels like it places a lot of load on the wrist and would hurt when the weight gets really heavy.
Although in Starting Strength Rippetoe recommends the suicide grip because of the natural wrists angle, I feel that the reason top powerlifters use the full grip is because even though it puts the wrist at a very awkward angle, it also pushes the elbows forward into the "correct position". Many articles on Elite talk about the elbows down and forward thing.
It all boils down to personal preference though. If you don't like the wrist angle go suicide. If you like the angle the elbows are in with the full grip, go for that.
Goals for 12/31/11
Stay consistent on one program