I too had abysmal wireless when first installed back in May. I tried Modem Mode with my old Linksys 54GS Router for a while. I then experimented by setting the Superhub SSID and security to the same as the Linksys. This enabled a quick swapout to compare performance and found these steps useful:-
Use InSSIDer to discover which channel(s) are in use nearby. Choose a channel, i.e. avoid Auto, which bridges a gap, in my case Channel 8 on 2.4Ghz band.
I then locked the speed down to 144Mbps.
R36 firmware started rolling out on 13/07/2012 see here
and I installed this within the last hour. Everything went smoothly with wireless laptop, desktop, Blu-Ray Player and TV all connecting seamlessly as does my iPhone.