I had access to both of them at the store I work at and had a substantial discount as well. I went with the 2700.
First, the 2700 has a much better GUI. It is not only user friendly, but pretty. The "60's computer" look on other receivers (including the 4306) is just tacky and unrefined. Yes, it gets the job done but for the price I expect more.
I listened to both receivers and I liked the Yamaha sound better. Honestly, there wasn't a big difference. In fact, I'll bet most of the (small) difference could be attributed to the room EQ and auto calibration settings. I liked Yamaha's YPAO better than Denon's Audyssey EQ. The Yamaha has one super sweet spot but the other seats still sound good. The Audyssey EQ in the Denon attempts to average out the room response for multiple sweet spots. I prefer having one sweet spot. The way I look at it is, averaging is a compromise. I'm not saying the Denon's Audyssey sounded bad, it didn't. I simply prefered Yamaha's system. Another plus for Yamaha, their system has two parametric EQ bands on the sub.
I wasn't able to try the music streaming feature on the Denon but I have been using it on the Yamaha. Sound quality is excellent but navigating my large music library is a pain. There is no easy way to get to specific artists or songs because they are arranged in a gigantic alphabetical list and pages load very slowly. Scrolling through takes forever. I have overcome this by creating playlists.
Featurewise the two receivers are very similar. It comes down to personal preference. Both are excellent receivers and you would probably be pleased with either one. I say the Yamaha gives more bang for the buck.