"In a match if you have to do a real tac reload, just catch the brass and loaded cartridges (SSR) or the speedloader (ESR) and drop them in your pocket."

That actually used to be recommended in the rule book, just like a lot of other stuff treating the sixgunner as a second class citizen.
It is simple and convenient but in the rare case of having to USE the ammo saved, sorting it out from the empties will take a lot of time.
There are better ways, but they are seldom needed; I recall like twice ever.

"If the pocket you drop the TAC load rounds in happens to have a speedloader or moon clip in residence, the reload gets a lot easier. One move to drop rounds, simple move to pick up loading device, and much faster than bringing the hand out from the pocket... empty... and having to dig under a vest."

That works, for sure.  As I understand it, you are required to carry reloads distributed the same way all the time.  I don't see two on the belt and one in a pocket as a disadvantage for anything, though.