"Crisp" on/off thumb safety is usually determined by profile of edges of thumb safety and to some extent the plunger nose profile itself.
More rounded corners on thumb safety with a really/radiused rounded plunger will create a softer/mushier on/off, conversely sharper edges with a "pointier", less rounded plunger a harder/crisper on/off.
The depth and lead in, to the plunger "socket" of thumb safety, contributes a great deal in the feel as well.
The plunger spring itself should be similar in both the Colt and SA, but who knows. Obviously you could switch plunger assemblies between pistols and see.
A tip on the plunger spring allowing the plunger to launch; a common mod is to kink a coil of the center of the plunger spring. This will nearly always result in plunger assembly being contained in the plunger tube when thumb safety is removed.
I basically crush a center coil with some quality needle nose. This provides enough friction to prevent spring/plunger from flying out of plunger tube- while still providing ample "spring" for the plunger to work on safety.
A true "Gun Guy" (or gal) should have familiarity and a modicum of proficiency with most all firearms platforms.
Bookmarks