That approach was done at one of my clients ponds. Unfortunately when the pond was dug, there were a few GSF in the wet area that he didn't know about. The slow approach let the GSF multiply rapidly, so much that the RES and YP that were stocked never had any recruitment.
I may get to learn that lesson first hand, because I suspect that to be my situation. Fortunately it is my refurb pond and not my main pond, so not quite as big of deal.
I have heard others say that with BG they reproduce enough to eventually crowd out the GSF to a lower level. But I can see with the RES and low reproduction rates it could be a problem.
