I think when they said "the first 3" are discontinued, they were counting "Grape Jam" and "Wow" as two separate CD's . . . anyway, I agree with you the "first three" (not including the Jam separately) are the ones to get.
I think "Grape Jam" is basically the same as the third record from "All Things Must Pass" . . . both of which were no doubt inspired by all those "Super Session" jam-in-the-studio records. (Not worth much in other words!)
PS - of course "Grape Jam" was a bonus disc that came free with the "Wow" LP (another overzealous promotion by Columbia, though probably worked out better commercially than the disasterous "release 5 singles on the same day" strategy for the first one!)