NVidia driver 347.71 has been released as a hotfix driver that addresses the issue of GeForce GTX 900 series cards being unable to apply optimal settings in GeForce Experience with MFAA support.
NVidia support page describing driver and providing downloads: http://nvidia.custhelp.com/app/answers/detail/a_id/3636
Driver 347.71 is r347_52-2, DriverVer = 02/26/2015, 9.18.13.4771