I would have agreed with you a few months ago, but I'm not so sure now. . . . I think that the better stability of magnetic cubes changes the ideal grip slightly: you have to grip a non-magnetic 4x4 a little more precisely, which is easier to do with a 60mm, or even a 57 or 58mm cube than with a 62mm. A 62mm, on the other hand, is a little easier to, for lack of a better term, "throw around," provided it has sufficient stability.