Sensi's not as bad as it's made out, and the A4 is a great gun. I'm still shooting one as a primary (but don't go by me, I haven't played in over 6 months. I basically just tinker the hell out of markers, I don't actually play with 'em anymore
). COPS was Sensi's predecessor, featured on the IR3, and gave Sensi a bad name before it even had a chance to prove itself. COPS required quite a bit of fiddling and setup to get it consistently preventing chops. Sensi on the other hand automagically configures itself, and works quite well in my experience. But with the modern angels, you can get the pressures low enough that you can easily pinch balls instead of chopping them anyway, even if your Sensi, or eyes on the A4 Fly and up, fails. The A4 will probably be lighter, it's every bit as fast or faster (not really a huge consideration anymore, seeing as how everybody's playing 15 bps anyway), easy as hell to maintain and a solid built marker. I might be biased toward angels a bit, but I've got a ton of experience with 'cockers too, and I'm a huge fan of them myself, but I think most people between those two gats would be happier with the A4. 'Course the standard, reasonable, unbiased response is: Try them both yourself and see which one you like.