I am biased against FCoE because it’s too new to be blithely and broadly recommended for production enterprise use. That’s all. Yes, the standards are standardized and there are products extant. But that’s not enough for me.
I know that a number of FCoE-related standards are settled, and I know that there are products in the market and even some limited multi-vendor compatibility. I even accept that some customers are deploying real “Full Monty FCoE” in production. But I just can’t recommend that technology yet: It’s not prudent, widespread, and low-risk, so I say it’s not ready for prime time.