Naturally, you are going to get a lot of biased opinions here. For example, I had a Look 595, but now ride a Specialized Roubaix SL2. Love the SL2 so much, I would recommend the Specialized. However, just saying that doesn't do you any good.
We are all different. You're a bigger guy, and probably have more power than most of us, so what works great for us, may not be the best for you. I know I'd be reluctant to try to sell you on how stiff the bottom bracket feels, etc being 5'11" and about 170.
I think you really just need to find some demo bikes and ride them. I know even the small LBS has a Specialized demo program where I was able to demo a Roubaix on some rides I knew before I purchased mine. Competitve Cyclist will ship you a ready to ride R3 that you can demo for a week. The cost is a little steep at $300, but that covers both outbound and return shipping. More info is here.
Cervélo R3 Demo Bike - Competitive Cyclist
Good luck, and let us know what you decide. I know a lot of people are probably envious of the decision you are making.