I have a tube of AS5 and a tube of the paste that came with the 212+ when I initially got it. I didn't have my AS5 when I had to reinstall my cooler once and I didn't give it much thought. I think I did a comparison of my 8320 at stock clocks at load with the CM paste and the AS5 a while back. Degree difference was 3ish degrees Celsius or so at full load and negligible at idle. Unless you're expecting to be terribly bottlenecked by temperatures when you overclock, just use the stuff it comes with. No point in going out of your way for something different. I've used that tube at least 2-3 times and it's probably got enough for another use. I'll use my AS5 next time as there is SOME difference, but all in all not worth the effort unless you're going after a mad overclock.