Re: Benefits of New Routers?
2.4 and 5 ghz are just wireless spectrum. (iirc) 2.4 ghz works by passing really well through walls and 5 ghz works by bouncing (albeit pretty crappily) off walls to your equipment. The best way to describe the spectrum (from a performance standpoint of course / imo) is like having an economy seat on airplane (they're cheaper to buy and are as such, more crowded) vs. business/first class on the 5 ghz. The area is less crowded but fewer devices uses it.
I have yet to use 5 ghz well at home, granted I have an older router and I don't have any personal experience with how the 5ghz band works on newer routers. 2.4 ghz seems to cut it well enough for me, even (wire-lessly) maxing out my 20 mbit cable modem connection at home. So as far as "internet" access goes, either 2.5 ghz N or even G should suffice.
HD streaming over N vs. G will differ, it depends on the architecture of your residence, again, running tests will help you determine what suits your needs. But I don't think using N over G (with the right hardware) will make that drastic a difference - especially using stock firmware on the router (I don't know if there is custom firmware available for the MAC Wireless, I know there is for Linksys i.e. DD-WRT, that completely transforms the Linksys router from sponge-bob square pants type personality into a Thundercat).
The benefit of 5 ghz is that, being less crowded, it can fly, especially as the HiDef quality climbs towards uncompressed bluray, but the hardware needs uninterrupted and un-blocked connectivity with the router.
If that seems like I'm rambling, PM me.