I'm on 30meg and get a 30meg download on wireless with the band set to 145. I find 145mbps to be more stable than 300mbps however I don't know what effect 145mbps has when you are on 50meg.
Anyway.......
Try installing
InSSider and manually go through all the channels until you find the one that gives you the lowest RSSI value. Note that all the RSSI values are negative. The lowest RSSI indicates the strongest signal. -29 is the best I can get and I have loads of competing routers around me.
In spite of R30 I find that the longest the superhub will stay up for me is 14 days it will then either reset or if it stays up it will lose the wireless completely, wired connection then runs very slowly and on accessing the HTML interface I find this too is very slow to react. As always it's fixed by power cycling. It seems that the memory leak may not be entirely fixed.
If you have a decent router already then modem mode will probably be the best way to go.