Stereo mic, do you mean even larger PMC's, or was that a little swipe, suggesting another brand may be preferable? I can't see any sane person having larger speakers than brizon to be honest.
With regard to tri amping, I personally find the idea of the extra cost, extra cable and extra space to be a nightmare! I'm happy if the changes are worth it for some people, however I'm sure it's a clear example of diminishing returns at work.
I know a (nutty) guy who upgraded from large passive PMC to active PMC. He didn't do so on the basis of sound quality. In fact he makes no claims regarding an increase in quality at all. He made the change due to power handling requirements. Previously he managed to melt the passive x-overs due to their inherent heat wasting design, plus the prolonged high volumes he was running. The active version runs much cooler, so eliminates this problem. I presume this is why a lot of clubs, studios and PA applications use active rigs as a safety precaution.
Secondly I have been told by an employee at Cornflake (Dominic I think) that taking PMC's to active setup is not always worth it. In his opinion using six monoblock Bryston amps with large PMC's can sound quite impressive, but the music is more seperated, rather than the more cohesive sound you get when using just one pair of Bryston monoblocks passively. I can only assume that going active will be an improvement for some people, but not eveyone. That's a lot of extra mess, space and money to find out!