DMRBG, I think your experiment is great. If you could get cold tolerance, snail appetite and resistance to stunting I'd be very interested. I've been toying with the possibility of adding single sex PS to a YP/SMB pond for snail control. Unfortunately, one mistake with the ID and the whole thing could nosedive.
Speaking of which, how fecund is the RES x PS hybrid?
I personally cannot answer that question from experience yet however; from what I have read so far, I expect that you would need to carefully manage the population.
