To be fair, I don't think I've ever played on a GC1/2 that had non factory cushions. (I def played on plenty with the factory cushions, even last year, that played awesome.)Classic billiard site claims that Brunswick superspeed is interchangeable with all GC1or2 tables without negative effects. They say that it is a myth that K55 cannot be used on such tables. IDK - just saying what I read today - everyone seems to have an opinion - as a guy looking now for a GC myself - I sure would like to know the reality in case I find a GC requiring new rubber.
I'm going by what I read on here over the years, and stories of belt sanding the rails to use K66, or put K55 and have the wrong size and/or wrong cushion angle, etc etc.