I think there are advantages and disadvantages of both designs.
Not having clay and silt running through you primary box is huge.
Doing a lot of thinking lately about how to build a good trommel.
Just depends a lot on the type of material you are running.
I've seen many trommels with just a 3/4" screen and single box.
that is what i use also , 3/4 minus thru 1 run of sluices , 12inches at top 13 inches at bottom 16 feet long , , I'm very satisfied with my current performance , but i do not run the same volume as your pics
Does anybody know of any good online videos of the big trommels that they used to run in the 1930's?
Someone should still be using something like that since they were built like a tank.
I have a single panel of screen from a 1930's drum and it takes two people to pick it up.
Nothing that would wear out very quickly.
---------------
So far the best idea I have seen is a secondary small diameter drum that spirals the 1/4" minus back up alongside the main drum.
That way if you had material with a lot of fines, you could speed the secondary drum up without affecting the washing action of the main drum.
Not sure how they weld the spiral into the small diameter drum...must be an insert.