So on HX, you're playing with half the available cabs and third of the available mics with those cabs, which makes for (20 cabs) * (5 mics) = 100 IRs per amp... doesn't sound to me you've filtered out your much IRs at all, let alone to 98%. I think that's one of those things one does once and move on, no? Do you really do that on the regular? And even if you use 100 IRs per amp, and supposing no overlapping IRs at all between amps, do you use more than 20 amps?
Anyway, I don't think that's how most people make use IRs, I think your case might be pretty unique.