I might as well chime in here too. I always noticed that my M22's and VP150 did not sound the same either. I never really noticed it while watching a movie, so it didn't really bother me. I only really noticed it when setting my levels. (with my trust Rat Shack meter) They sounded very different with pink noise.

I don't think the difference is quite as noticable with my new M60's. I'll check it out, and try some of the placement "tweaks" you mentioned.