Having done the contracting gig myself, I don't find using an adapter as a big deal. Bigger issues IMO is that the rMBP screen is still more glossy than the Macbook Airs...
Yeah, I'm with you on that too. I bought my MBP with a matt screen for that very reason. Glossy is a big no no for me. I don't care if its '75% less reflective then the previous model' it's still 1000000% more reflective than a matt screen and my office has windows! (slight over exaggeration there, but you get the idea).