If you read up in the http://androidforums.com/ascend-all...4-gingerbread-current-version-05212011-a.html thread, it will tell you that with this newest version of the MetrOFF, you do NOT need to modify any APNs. Infact, it also tells you that your setting are coded in, just not showing when you view the APNs.
Sinner that statement won't apply to all Ascends. There seems to be some major differences in the way the MMS is fetched from the phones of the same model or type. Once you enter the system's APN editor it's going to require a APN in order to save. #777 works just fine so that shouldn't really be a concern anyways. I really wouldn't use it as I use APN editor and it actually shows the list. Even importing a backed up copy of the APN from the factory state into CM7 does not work and if that's the case then there are going to be problems.
I have CM7 correctly flashed and working fine. After rebooting into the sytem and then rebooting to flashing MetroOff, rebooting, opening APN Manager and changing the 27 to 16, I am able to send and receive txt, send picture messages to any carrier but only receive them from Metro PCS members (even by sending them to myself). I cannot receive them from any other carrier or source. There seems to be a glitch or hole in the ROM update for our m860 model/type that is preventing the mms from fetching the data from outside carriers.
There doesn't seem to be a quick resolution because not everyone has this issue with their ascend so by default most are quick to say we didn't do something right.