Harold,
Over 25-years worth of GSP's here - I agree with the good traits mentioned on this thread. The detractors don't know much about handling GSP's.
I hunt pheasants 90% and grouse 10%.
That said, your profile lists Vermont as your location - a GSP (or any pointer) might not be my first choice for grouse hunting in thick cover that stays thick much of the season. I'd probably go with a Springer.
