I chose the 525 because it had a better feature set for the money (ie, 7.1, not 6.1), and I'd heard that Marantz had some serious quality issues with the 7200 (7300's predecessor). Of course, at the time, I was comparing to the 6300 and the 7200, not the 7300. I picked up the 525 for about half price on onecall.com as a refurb. Works great!

I am the Doctor, and THIS... is my SPOON!