drummerman:... and if you spend that sort of money you should add a Supernait to your list. Not for me but you may like it.
I've just moved from a Creek OBH-12 pre-amp and Arcam P35 & P38 power amps (so that could be as close to your set-up as anyone on the forums is likely to get) to a Naim SuperNait. It doesn't quite fit all your criteria because it only has one set of speaker outputs, but then you could probably get your cables re-terminated.
But I would suggest that even if you moved to using the SuperNait single-wired (as I have done) then if you like the Naim sound it would probably represent a profound upgrade from your current amp - it certainly has for me.
But then you may not like the Naim sound - it will be very different from what you're used to. The Arcams err on the warm side and I can tell you that the P38 is not a lot different to the P35. The Creek is very neutral though, so by reputation I imagine that your MF enhances (or exacerbates, depending on whether you like it or not) the warmth of the Arcams.
The Naim sound is brighter at the top end, extremely revealing across the frequency range, the bass is superbly deep, tight and textured, and the whole sound has a very direct, punchy and vivid presentation. I was looking to get a little closer to what live music sounds like and it absolutely fit the bill for me. The icing on the cake is the dynamic range - compared to the Arcam power amps (both of them bi-amping) the Naim's ability to respond to changes in volume (i.e. naturally occurring in the material being replayed) and to keep all elements of the presentation rock-solid is just amazing to me. I think it helps that it obviously matches very well with my PMC speakers, which in hindsight i don't think that the Arcams necessarily do.
Not sure how it will go with your MAs, but I seriously suggest you give it a try.