dj I have the 5700 and love it, but I think the 3600 is a good piece and would highly recomend it. This way you could buy a Pronto to go with it because the Denon remotes are terrible! If switching surround speakers through the remote, componet video switching and 7.1 inputs are not a concern then get the 3600.
I assume you are talking about the DTS 3600 but you may find a good deal on a last years 3600 with no DTS if this isn't a concern. One thing to note is the # of digital inputs on the 5700 even if you think you might not need them now, think future. I use 2 for satelite 1 for DVD 1 for LD 1 for CD and the in and out for Mini Disc recording