Thanks to everybody for their input. Couple quick questions back for the group.

-- What are the downsides to HSB's? Will I need to replace them every few years since they don't reproduce much/at all? If they do reproduce, are the later generations desirable? Can they coexist with LMB, or is it one or the other?

-- SMB is an interesting idea, but I assumed a pond in my warm climate may be too hot for them? Anybody have any experience with SMB in ponds in Virginia? Pros/cons?

Thanks all -- please keep the advice coming. I really appreciate it!