So a plane with a huge span, swept-wings, big ailerons on the tips, and most of the mass in the center of the plane, and on the tips with nothing in the middle would get the best roll rate
In a word-NO.
Best roll rate planes have their mass in the center, powerful ailerons, short wings and having hydraulic boost doesn't hurt a bit. Examples T-38 and A-4 Skyhawk. They'll bang your head off the canopy if you aren't paying close attention.
Now in the big iron stuff, with load distributed along the fuselage, increased AOA causes the fuselage to get out of line with the actual roll axis and that increases roll inertia and should decrease roll rate acceleration.