As to wireless being no good for gaming applications, with the stuff you generally get at wal-mart, no it isnt. This device just looks like another walmart special. Bottom line: Garbage in garbage out. There is no way a soho device is going to deliver 450mbps at any kind of range with those antennas. MIMO helps, but not enough to get 450mbps. I also wonder how wide the channel is for this. 802.lln would classify this as MCS 23, and the 450 would be at the BEST of conditions. Its then going to fall to something slower, and also remember 450mbps is AGGREGATE throughput. Meaning, 225 theoretical max in either direction. I would be surprised to see over 140 come off this device from its wired interface through to wireless, much less between other wireless devices on the same AP. Noise is also going to be a factor, as if you live in an apartment there are easily 4 or more AP's in range of yours, occupying the now huge chunk of spectrum these 802.11n 2.4ghz devices require to do high throughput.
Now on to some better stuff: If you want decent wireless latency and good quality link between systems you have to shell out some bucks, or build a good one yourself. Cisco/HP make a high quality unit that I get around 1.2ms of average loaded latency on when using them on the corporate net, with an average load of 12.8mbps going through them on the wireless interface at any given moment. These are not 802.11n either, just b/g.
As far as the dual band goes, thats about pointless because the 5ghz band is not as good at bouncing off of things as the 2.4 spectrum is, and has less range even in open air, but has less noise. If you want decent MIMO speeds and latency, you gotta get carrier class hardware. Google ubnt nanostation m2 (The airmax line) and get one of those. The antenna makes placement key, but it will yeild far better results than anything off the shelf for off the shelf prices. It can even be used as a SOHO router with a single ethernet port to downlink to a switch. Set power to 17dbm and let it cook. I have a 2400 sq ft house, placed this bad boy at the ceiling of the back room facing towards the rest of the house, and in my living room I get MSC 13 (240mbps) and it will do most of it. (benched from wired side @ 102 mbps, wireless to wireless does 81) Latency is 0.9 - 1.8 with -80 or better signal.