I'm using two ASUS RT-N12 routers with firmware Tomato Firmware v1.28.9054 MIPSR2-beta K26 Std.
When I setup WDS with AUTO (N/B/G) and WPA2, it works… and it works FAST!
But after several minutes, the WDS between the two routers drops out and they no longer connect. Power cycles required.
So, it has the potential to work VERY WELL… it just has some bug that won't allow it to stay connected very long.