Post what set you're currently using and you might find a few more replies.
I've decided that I am just going to completely drop Rest + Sleep Talk from the current analysis, as I can find no convincing reason to further keep it. From personal experience, I can say that the new metagame is not friendly towards Metagross in terms of walling; this is because, ironically, Metagross gains few handy resistances to build upon with its Steel / Psychic typing. I'd also like to note that while the combination of Steel + Ground seems to be good on paper, it just doesn't cut it when Metagross is trying to deal with the Pokémon it could counter by running Rest + Sleep Talk. For example, Starmie can easily Recover off any damage taken from Earthquake while Metagross will be doing nothing but wasting precious PP. Otherwise, noting its resistances to Normal, Rock, and Grass, Metagross can only truly wall the
uncommon Normal and Grass types; in either case, Celebi can still set up on you assuming it has Recover / Leech Seed, and Blissey and Snorlax have no real reason to stay in on you considering you have a good chance of getting an Attack boost.
Is there a reason not to run max attack on the CBer other than the "arbitrary not OHKOed by a bunch of stuff" point that's really not much different from max attack's defense spread? I haven't read a convincing reason anywhere :/
I think you are forgetting that Metagross already has a colossal 398 Attack with the given EVs, which still deals a tremendous amount of damage. The main point is, reducing Attack by a total of five stat points is nothing compared to the ability to survive a Choice Banded Earthquake from Dugtrio along with being able to outspeed Skarmory, Magnezone, and enemy Metagross, although the latter reason does not truly support my case as you'll be stuck on a move anyways.