You are correct, the new cushions are the lil bit bigger and change the ratio a small amount. My opinion: All tables diamond system is a bit off from one another anyways. Anyone who could tell it was off that tiny amount can adjust their game(gotta do it on every different table) and play their game.
Wondering what you think that measurement is and some sort of explanation of why you think the table will play slow and bank improperly. Let hear some fact based answers.
Just gonna put this here: I have mounted many many set of cushions on Anniversary, Centennial and GC 1, 2 and early 3's and the craziest thing in the world keeps happening: the nose height is correct. No ball hopping or biting under the rail. Never had someone call me telling me their table plays bad. 70 something GC's, 21 Anniversary's and 5 Centennial's in the last 7 years.
While talking with my clients all of this rail stuff is just a part of my sales routine, I let the customer have all the info and let them decide what they want. I have had about 6 sets of rails converted for the ones who want them as close to perfect as possible, THANKS JACK Z.!
So to answer the OP with my opinion: as long as you have someone who knows what they are doin: go for the new Brunswick SuperSpeed Cushions, you will be just fine.
TFT