I’ve uploaded two test images based on OpenWRT r35905 (Linux 3.8.2) for the TL-WR720N here :-
Both Ethernet and WiFi appear to work as well as the mode switch. Both images are similar to the WR703N images but with less things (mjpg-streamer ser2net dropped). I had to cut down as it appears the newer kernel is significantly larger [either that or I did something wrong].
I will upload the repository and packages tomorrow if I don’t find a better way to squeeze more goodies in.