Firstly I must say a very good job this firmware is.
I noticed a bug with this firmware http://sourceforge.net/projects/tomatousb/files/Experimental%20%28beta%29/K26-MIPSR2/tomato-K26USB-1.27.9047MIPSR2-beta16-vpn3.6.rar/download.
When router establish connection with openvpn server it just reboots. In /var/log/messages there is no error whatsoever. I just see that router connects with openvpn server and then it reboots.