I don't have the SR5300, but I have the 5200, which is almost exactly the same receiver. I believe the only difference is having "offical" DTS-ES discrete and DD-EX codecs for the 6th channel, vs the 5200, which used Marantz's own codec to extract the rear surround channel.
As for quality, I bought my 5200 as a refurb about a year ago, and have had NO problems with it whatsoever. It has run perfectly. The way I see it, refurb's have had a once over or a repair done by hand, and have been scrutinized more then a random one off the line. I think the cost discount makes refurb's a great deal.
Yes, the it does take a fraction of a second for it to recognize the digital signal when you start a track from a stop. I believe other receivers in the price range do this as well though...
To my rather untrained ears, it sounds great. Hi-FI Magazine (a fairly reputable british mag) did a review of the 5200 with similar entries from Denon, Yamaha, Onkyo, and one other (Pioneer I believe). They choose the 5200 as the clear winner in both surround sound, and two channel stereo.
Certainly it's at least worth listening to; I've been more then happy with mine.
