Most of the tree guys around here run 20" B&C on 460/461s and have 660s for the bigger stuff (36" usually) and top handles for the little stuff.
I run 20" bars on 4 saws, 2 ported 60 cc saws, and 2 modded (but not ported) 70 cc saws. The 70s have a bit more grunt (like if your worried about getting pinched on the log pile). The 50 cc saws have 16" + 18" and the larger saws have 24", 28" and one with 36".
I put a 24" bar on my 044 a few weeks ago to fell a Ash that was just over 20". Put a 20" B&C back on it as soon as I got home, it just handles so much nicer with that on it. The Stihl 20" E bar is very light, much lighter and better handling than a 20" ES bar.