As usual it's different from gun to gun. My most accurate .177 is a Katran, which shoots pretty darn hot, at almost 20fpe, shoots Benjamin Single Die better than almost anything else. It is not the least pellet fussy, so the difference is small indeed, but whether it's conditioning my mind, or what, but I shoot better with them. I use AA and JSB 10.3gr also, and like them, but I'll take the BSD every time so far. Maybe the harder alloy is better for higher velocities, but my R10 also shoots them very well also, and it is a good 100fps slower.
I'd love to try some of the BSD in .22 and see if they are as good in my .22's.