Well if you can do that, it sounds definately like a no brainer. I used USAA for the mortgage on my current house, and to say the least, I will never, ever, ever, ever EVER, finance anything through them.
Getting the mortgage from them was the easy part. after we closed, nothing but problems. Like a typical mortgage, I had an escrow account for my home owners insurance (which was through them for a bit) and my property taxes.
Make a long story short, every month I would get a check from USAA stating an overage in my escrow account, then like clock work, 3 weeks later, I would start getting calls from USAA stating my escrow account had a negative balance and as such I owed x amount more on this months payment (which oddly enough was the same amount they previously sent me). after a lot of arguing and basically telling them to come get the house that I wasn't making another payment until the closed the escrow account, they finally did. I have closed all my accounts with USAA except my auto insurance, because their customer service is horrible at best. I also had issues with changing my wifes name on the title and finance documents after we got married.
About a month after we closed they sold the mortgage to GMAC, but I still have to deal with the tools at USAA for any issues on the mortgage. Since I closed the escrow account, cancelled my homeowners insurance, closed all my bank acccounts with them, I have not really had any issues.
I recommend not using them, as everything is great, until they get you signed, then they treat you like crap.