What I can advice to the users with low resolution/refresh rates, is UseEDID "false"
It's a must if you have a monitor that lies about its capabilities (like my 19" "professional" iiyama).
My Ti4200 also worked with 9626 [excluding compiz/beryl, which technically worked, but no window decorations showed up
], but suddenly started crashing every glx app with 9629. Is there some workaround, some new beta 9630, or do we really have to downgrade?