I did almost this last summer with the Vette and it was the smoothest car buying experience I've ever had. We finalized the trade in amount based on pictures, and I did the dreaded Business Office Upsell meeting by phone (she sounded as gorgeous and well dressed as I'm sure she was!). The only difference was the paperwork wasn't signed until he showed up with the car.
If it's a reputable dealership and you KNOW it's the car you want, I wouldn't have any concerns doing it. I wouldn't be relying on that "money back guarantee" for anything other than the car wasn't was as represented, not because of something like "oh, the back seat isn't as roomy as I expected"