I just tried the latest DD-WRT (v24 RC4-preloaded) and also v23 SP2.

v24 removed IPv6 support, with v23 WPA-PSK didn't work (WPA, WPA2, WPA/2 mixed, TKIP, TKIP+AES) - even though the AP said connected and DHCP lease granted, the connecting station saw EAPOL frames (!) and never got the DHCP lease, although it did receive IPv6 RA broadcasts.

Back to Oleg's firmware. No nice bandwidth graph, instead it works and does what it needs to do.