For us I would be so bold as to say there is a double benefit in our pond. Of course different species, different locations, temps, you name it there are all kinds of variables but what has convinced me is how much more interest there was at feeding time with the AM.
Twice as many fish feeding and twice as many species. maybe an all BG pond someone might not see the benefit but with our paticular situation the AM just worked better at least by appearance at feeding time.

1/2 acre 14' Deep. LMB, WE, YP, HBG, BG, Rainbows.