Ah, yeah. I've tested it and it certainly doesn't give you any xp or grey tech when you re-installed the latest patch

I assumed that it would work because after finishing a co-op mission, I saw the logo which shows that the data is saving. Got me fooled there.
Imagine if this worked ... lol ...
Anyway, the old glitches do indeed work (I have tested them.) Just got out of the Orick map via the Orb glitch now. Lol, ain't it so fun to explore !
This method works because the co-op offline component doesn't require PSN, that's why you don't get a PSN pop up demanding you to install the latest patch.

Sorry, I don't have any vid equipment to record. :p