It is entirely possible that by purely recompiling with the /LARGEADDRESSAWARE flag, that they can grant FSX access to more memory on 64bit OSs, even though the code is still 32bit which would vastly reduce OoM errors. Typically this can grant an increase from the default 2gb to 4gb, and in itself would be a worthwhile change - and if they haven't done so already, I'd be very surprised if it didn't follow as an early update.
http://msdn.microsoft.com/en-us/library/windows/desktop/bb613473(v=vs.85).aspx states:
A similar technique has been used (by reverse engineering/3rd party patches) to patch games such as Fallout 3 which also suffer out of memory issues from large collections of add ons, and has worked very effectively there to improve stability with large amounts of add ons loaded.