I installed a Buffalo wzr-hp-g301-nh at short notice when a befsr41-c went titsup at short notice. Despite not liking Buffalo for historical reasons, I do think this unit performs well: range is way up, the two twiddly antennas have proved useful, the unit runs much cooler, and it has way more spare memory. I put dd-wrt on it, although recent units come with Buffalo-branded dd-wrt anyway. One of the nice features in some markets is auto channel search: it will find the best channel to operate on.
Also, depending on your jurisdiction, the "there are only 3 interference-free channels" may actualy be "there are only 2 interference-free channels", as the highest-numbered channels may only be allowed to operate at reduced power.
Something like inssider might help you locate the best channel for your location, and then you may not need to changer routers anyway.
Another possibility is addign a wireless bridge to the target area. Some wireless routers can do both things at once (hello Buffalo again).