A gsf is a cross or mutt. I like them. They only spawn once per year and, especially in the presence of bass are unlikely to over run a pond. They can’t keep up with bg multiple spawns and cause damage.
I’ve often asked what happens when this mutt back crosses, over several generations, with other sunfish? Do they also only spawn annually?
A couple of years ago I caught a huge one, probably 11 inches, and that guy/gal is the biggest sunfish I’ve ever caught. The only gsf I saw in it was the green area on the jaws. The rest was pure bg. They fight, when hooked, differently than bg.