A new dashboard update referenced 2.0.12611.0 is available since this morning on Xbox LIVE™ and incorporates new AP2.5 protections compatible with the new SSv3 games.
Thus Lite-On® and BenQ® flashed drives are targeted and in case of update with this dashboard it will not play an SSv3 backup game like Fable III™.
However, it seems that for the Samsung® and Hitachi® drives there is no possible AP2.5 verification in iXtreme v1.X (LT?).
Similarly no checking for all the old games (SSv1 and SSv2) whatever the drive.
The implications for use of online backups are still unclear also the precautionary principle requires owners of flashed consoles not to play games with new SSv3 and, by extension, to be vigilant in case of banishment for old games users (unlikely).
Level response, the team of originally iXtreme firmwares announced off-and-already working on a LT+ that would solve these vulnerabilities.
At this time no date has been advanced regarding the availability of this new firmware.
[10.11.07 Update] If you use an SSv3 game, the AP2.5 check will blacklist your console which will lead to a ban when connecting to Xbox LIVE™.