Baitcasters shine with heavier line and bigger baits. That's why you see all the bass guys using them. They're throwing 3/4 oz spinnerbaits on 25# mono or 60# braid.
I use nothing but spinning reels (unless I'm fly fishing.) They do fine with the baits and lines I'm using. As far as this:
... I think line memory has more to do with the line than the reel. And for crappie fishing, do you really need to go heavier than 8# line?