It seems sort of dumb to have bought a Blu-Ray player with wireless capability, and then not use that feature. On the other hand, it seems sort of dumb to have a router with dual-band capability and use just one band. Let's just say that I probably could have done a better job of thinking this through. 
I'll let you know how it goes with the DAP-1522 as a 5GHz wireless bridge.
A couple of things that may help, WPA2 is faster then WPA. The AES setting is good. Found this out the hard way. 20 Mhz channels overlap, so if you have a close neighbor using channel 1 and another using 11, the choice for you should be 6, I know they say stay away from 6 because that is where routers default, but if it is open, use it. Channel wise you want to be as far away from the other guy as possible.
I have used mine for HD video (1080P) on 2.4Ghz, 5 Ghz and wired, all work just fine. My speed is 20 x 1 and I share it with 3 other people. If I would have NOT been close enough for Hardwire, I would have went with 5 Ghz, I live in Southren California and the 2.4 band is JAMMED. I share with 2 XBOX 360's, my wife surfing, daughter streaming music and sometimes video and NEVER have had a need for QOS. Back when my daughter was living with me, I did have 30 x 2 though. Never any buffering issues. One thing I have learned, the wireless loads up quick with Xbox 360's, a lot of small data transfers, especially when they are using VOIP to play games. So I added another AP to off load the gaming from the DIR-825. I never had a problem with G and N at the same time, but it will slow you down a little. Reading the radio specs for the router, the router puts out 3 or 4 milliwatts more in "G" mode then it does in "N". The radio chips in these are rated 14MW for "N" and 18MW for "G", not really a huge difference.
When I first put my new DOCSIS 3 Motorola modem on my system, I was getting 60 x 60 for about 2 weeks until Time Warner Cable reset my connection speed, I know this router will cook along! The first thing I would look at is the WPA vs WPA2, that made a big difference for me, even my kid commented on it! Hope that helps......