I am in the process of booking a fully paid BE ticket BOS-VCE-CDG-BOS. I first got the flights I wanted for timing etc on Delta.com and then ran the same thing in Expedia. The fare in Expedia came out a lot cheaper, 1200 or so. Is there any reason not to use Expedia. As far as I could see you could make seat selections, got a "real" Delta (AF) ticket etc. The only difference is that there was a 450 change fee as opposed to 250 (or waived) Am I missing something? Has anyone had bad experience with Expedia? Any reason not to do this?

Thanks for any info or experience.
Joe