Norm,
I have a pond that is a little over an acre that I stocked in april of 04 with largemouth bass, smallmouth bass, walleye, black crappie, bluegill, redear sunfish, channel catfish and yellow perch. I wasn't really concerned about raising trophy fish. I was more interested in a diverse fishery. In spring of 05 I caught 14 small white bass "sand bass" out of a creek and added them also but believe that they were to small and became part of the food chain. This past january a few friends and I caught some rainbow trout out of public lake that the state stocks in the winter. I'm going to see if the trout make it through the summer since I run a 50gpm well all summer that comes in at 56 degees.
Anyway back to the crappie. I know last spring that the crappie had a successful spawn. I had a minnow trap out last summer and nearly every time I pulled it in there were atleast a couple 2 or 3 inch crappie in it. The original crappie are 10 to 12 inches this spring and are on their nests right now. Anyways I know this doesn't help your theory out because my pond hasn't been stocked long enough to say wether or not a diverse predator base impacts young crappie but I might know more in a year or two.
