I currently have 2 xbox 360's, 2 androids, ROCKU streaming video, 3 computers, VOIP(ATT Microcells X2) and outgoing/incoming streaming video. The only problem I had was my internet provider speed was not enough, upgraded to TWC 2x15 and the lagging and disconnects went away. There is a "we" somewhere in there too, but I think it was too healthy for them.....
No special configuration needed, the 2 boys were playing each other in teams on some shoot em up and kill them war game on both of the 360's, one was wired the other was through WiFi, lot of screaming and yelling going on, but no complaints.
I like the DIR-655 too, it worked well in the above configuration, but I wanted the 5Ghz WiFi, so I sent the DIR-655 back and got the DIR-825, plus back then the 825 was the only one IPV 6 ready, I think the 655 is now IPV6 ready too. Also the new B revision 655 had just been released, but I could only find A4 revisions of the 655.
I am seeing 6-8ms pings through my 825 to LA(wired), I am 40 miles to the southeast. Better then the Cisco I had!
As furry said, 2 routers will kill you, if you need to run it, make sure the addresses are different. 192.168.1.xxx, 192.168.0.xxx, went through this with Vonage, weired things start happening if they are the same address range.