Clamp On vs. Set Screwed Gas Blocks

it was explained to me by a smith that if its a standard barrel contour to go with a clamp on block as pointing the barrel could create a hotspot but with a heavy barrel the set screw block is preferred and have less chance of hotspot
 
I have seen very fancy guns built both ways - I have a .750 contour Lothar Walther barreled gun that shoots .4 on average and has a set screw block. And my new JP has the clamped and shoots better than that with hand loads.

the number one concern for a gun that made of excellent parts is the barrel fit within the upper. Testing has indicated that either "hammer it in" tight oversized extensions or a steel shim and loctite increases accuracy by over 30%, and red loctite alone causes an 18% accuracy increase.
 
I've used both and havnt ever been able to tell a difference as far as accuracy is concerned. I do like installing a clamp on better though it's much easier to get aligned than a set screw type in my opinion
 
I am not convinced that one is better over the other in terms of reliability. When properly installed, I've never witnessed a single person have his gas block fail (key term being "properly installed"). I've used each type and haven't noticed a difference between any of them performance wise. Each was put onto a different quality of barrel though, so I can't really make an accuracy comparison.