Opposite feedback
I hate Gamma and Dunlop tennis balls with a passion. I also hate Penn Tributes (our coach gets them for our team due to the price, not a fan), but I enjoy the long lasting Penn ATP and Wilson Championship/US Open tennis balls.
I think it depends on what version of Gamma you use.
we go through a lot of balls at our 50 kid, weekly, free tennis clinics in san Francisco, and have tried all brands you can think of from wilson to penn, dunlop to slazenger and gamma to tretorn Z
The gamma pro tours are excellent balls up there with wilson us open for tournament play.
the regular gamma's feel a little light compared to dunlops but heavier than wilson and on par with penn. as for "hit", the regular and pro tour gammas are responsive, more solid than a cushier penn (in my opinion) and the lighter wilsons. they are on par with the dunlop grand prix in terms of "solid feel".
the practice gammas are such junk our group had to throw away 3 cases when the kids just would not hit with them. we even had a few kids start fooling around with them (hitting over the fence) in jest when they did not bounce out of the cans :0)
we used dunlop championships (the x-duty ball) for a long time (almost 4 years) and they last longer and have better bounce / felt durability than any other ball except the wilson us open which is a lot pricier.
the dunlop grand prix is the best wear/feel of all the balls we used, and the extra fifty cents was well worth the price.
we recently switched to gamma all surfrace court balls for our standard ball, and are satisfied. they dont last quite as long as the dunlop hard court but the price point we get them at makes it more economical.
part of the reason for our switch was that we were getting 3-4 cans without pressure and some felt defects from our dunlop distributor, and while dunlop was good about sending a new half or full case each time we had an issue, it was getting tiresome.
our choice for best ball ... DUNLOP GRAND PRIX
second : WILSON US OPEN
third: Gamma Pro Tour (avoid gamma practice at all costs)
fourth: Dunlop Championship
fifth: Penn Championship (avoid tribute or penn one)