The 24" bar is a LOT more usefull and changes the balance in a good way.
The 20" is much more handy in the tangles though, and it's a bit of a puzzle as to why. It just is, even if it dosn't make sense.
The best balance of speed and grunt seems to be a 24" bar, 8 pin rim and good skip chain, but get into twisted up and gnarly old Elm dropped into a bunch of Greenbrier and life is gonna suck without full comp on a 20" LOL!!!
Just the way it is unless ya brought along a 346XP, and then ya just don't notice.
Ya might want to try a 28 for a little while too. That way you can switch back to the 24 and justify a 395.
Stay safe!
Dingeryote