For viewing planets, it's a trade off between focal length/FoV and sharpness of image in this case. The longer FL's of the promaks will give you somewhat larger images, for the reasons I stated in my last post. But the SW will give you crisper views as there's no central obstruction, hence no light loss. The apparent resolution of the SW will look about the same as the larger promak, even though the actual Dawes Limit for the 6" SW will be less than the promak. That's due to the crispness of the image, so it's a subjective quality.
Both, in reality, are good scopes for planetary viewing, but if you want that "zing" to what you're seeing, the SW will trump the Promak.
Actually, Bob, if I were you and had the money to get both, I would (SW and larger Promak). Then you'd have the best of both worlds
