RE: GSP 72" Extra tip stalling
I had this plane for awhile, until the aileron CA hinges broke/stripped - but that's another story.
I too had problems of it snapping out of tight loops, etc. until I reduced my throws. It then flew very well. It is a good, nice looking plane but my TT Giles 202 flies much nicer with the same engine, at the same weight.
Reduce your throws and see what happens.