Yoyo,
My room seems very similar to yours: I also have the 60" SXRD and the 3806, and I am running M60s and a V150 in the front. In addition, my room is a similar size (16'x20') but with lower ceilings (9'). Given all that, I think there is a decent chance you will find the EP175 underpowered for your room. Thus, I would go with Option #1 and save for a bigger subwoofer down the road. This might also help stave off upgraditis!
Also, don't be shy about calling/emailing Axiom for support. I was ready to purchase M80s and they talked me down to M60s.
As far as the 3806 is concerned, I am rather pleased with it. The sound quality is noticably better than my Onkyo 575x (as it should be). My biggest gripe is that the manual is not well written, so it is a little confusing trying to figure out how to operate some of the more advanced features. I've never owned a Sony receiver so I can't compare the two.
Good luck and enjoy the decision-making process!
Bill
