Tom, there is no consensus of opinion among the several respected OEM designers that I have spoken with about this. One likes a single cap selected to a strict tolerance, another likes to parallel caps of roughly equal value but hand-selected to make tolerance, a third likes to pad up a base cap using .1-.33uf to make tolerance. I suppose that with this third approach it might be difficult to separate the effects of bypassing from the effects of making tolerance. Then of course there is Tony Gee, who likes small bypass caps and also combinations of different types in mixed ratios for flavoring. So far I have limited experience bypassing MR in crossover. I did try an MR base cap with a .01uf/200V Russian teflon. That combination was a bit edgy. I'd like to repeat that experiment with .01uf/350V Russian silver mica, which has a sweeter treble.