Bowlers Journal said there was hardly any difference once the 300T was polished. I think the 300T might be slightly more versatile, as solids are slightly more easy to manipulate the cover's finish. And if the 300C is not readily available, that makes the choice that much easier. You have your better choice of pin distances for more manipulation with drilling (even if the Differential is small, it's still dynamic core that be aided with the proper weighthole).