Price no object (at your prices, it's not an issue!), what speakers are best for 2ch music in a medium sized room? Will the m3's + sub sound better than the m50 or m60? Would the m60 be "too much" speaker? I realize there's a trial period, but I'd like to keep shipping costs down for everyone involved. :)

The M60s will not be too much for a medium sized room, and will the best sound for two channel from the options you've mentioned.