I have the same problem now on Kabini too, accel was working fine with xserver from experimental but now with first transition it does not, i have this EE in Xorg.0.log maybe it is relevant:
[ 16.761] (EE) Error config_odev_get_int_attribute called for non integer attrib 4 -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
