Posted By:
Hal LewisIf you truly want to maintain the current grades...
then I think you would HAVE to go with GAI...
because I don't think SGC or PSA would crossover the GAI 4 into a 4 slab of their own.

Obviously they MIGHT... but the odds are much better for you trying to crossover in the other direction.
After all, SGC and PSA want to project an image of being better and stricter than GAI (maybe they really are, I don't know)...
but I think that being VERY strict on GAI graded cards is something that they are going to do intentionally in order to preserve their market share.