I managed to finish Act III, mostly, in a co-op group in the wee hours last night. I took a few hours nap first in "preparation."
When our large group was about to tackle the final boss in its lair... oops. All but one of us crashed.
Strangely, it occurred at exactly the right time for me to order a certain something, so that worked out.
That was the most fun I've had in co-op in this so far even if it's mostly a cakewalk at normal. It helped to have a few patient people, folks who would drop TPs next to needed quest objectives, etc. The "pages" quest in Act 3 wouldn't spawn the 4th page, so I was able to start a brief solo session later and pick it up OK.
I have a couple blue skill gems now, but I seem to get about 60% green, 35% red, 5% blue. Just an eyeball estimate.