I just ordered from MacMall myself an hour ago, and their rep, Shawn, told me that if the computer shows up with any defects, it is returnable to them. If you have spent sufficient time with a rMBP to know it's for you, you are probably okay, and no matter what, it's still under warranty. I've struggled with the same dilemma...what if it's not perfect...but decided to take the chance since I've had good dealings with MacMall in the past and because I already know I love the rMBP. I hope I'm not posting next week about any bad luck.
MacMall has almost all the BTO configurations in stock right now, 5 Central, and ship into the evening. If you order from there, don't forget to ask for the Apple Insider 3% discount. It saved me over $100 off their already discounted price with no tax.
BH Photo is great to deal with for all things photography-related, so if you're sure you want the rMBP and know ahead of time you can't return it to them, I'd go for it, especially since they have AppleCare for $122. MacMall has no discount on AppleCare, but you could get the computer from MacMall and order the AppleCare from BH and come out about the same. Good luck!