I have had great success with GSH, there are some 5-6 ones in there after 3 years but they really deliver the forage for the SMB, YP, HBG and HSB. My pond is around 1/3 of and acre and it is full offspring, I can sit on the porch all day and watch random predators grabbing snacks. I think they're worth it over FHM if they have a place to hide and you mentioned structure is available.
