I love deafening my drummers
There really are so many variables, it's hard to say. But I think they are more subtle differences. The first 2X12 I built (now in the hands of another boarder here) was more closed than my current HT cabinet. And I replaced the original with a pair of 1X12's that just had smallish square cutouts in the rear so if anything they are even more closed. But I've played those stacked 1X12's right next to my HT cabinet in my studio, and the difference is subtle. So, I think the open backed cabinet, whether it is fully open or not, is pretty forgiving.
I had a 95 Groove Tubes Soul-o 75 head and cabinet, which was a pretty versatile little rig (you could run any power tubes you wanted without rebiasing because of the special Mercury Magnetics transformer) as well as Class A or Class AB, or a "pushed" Class A, like a really old Vox amp. But I also liked that the 2X12 cab had a removable panel on the back so you could run it open or closed.
One thing I have noticed about Jerry's original cabinets and the Hard Truckers iterations, is that the drivers are as tight on the baffle board as possible, with very little space between the speakers and to the edges of the cabinets. Some of the other cabinets floating around have a lot more space between the speakers. I wonder what that does to the projection and imaging from the cabinet? Did the Dead do it that way so that the Wall of Sound would take up as little room collectively as possible? Or was there a method to that madness?
They look more spaced here but that's because they are mounted from the inside.
how HT does it:
My (badly made) 1X12s.
The 2X10's I've seen on the Dead's stage (circa 1980 by Jerry's rig) were really tight, too, but they had the drivers mounted from the inside as well. I always assumed that was a little keyboard rig for Jerry before he moved over next to Brent ... a pair of 15's and a pair of 10s, which was what was over by Brent, too. He had his usual 3X12 (or was it a 4X12) to the left of his heads. I don't think they were Weir's speakers because you can see his cabinet to the right, with, I think, 4 12" Gauss drivers at the time.