Just to continue the discussion. I finally picked up the 2840 component on e-bay, so now I can make the big long tube. Here are some notes:
The 2840-2830 combo holds 4 sheets of 8x10 and cost about $65. The Expert Drum cost $400-500 and holds 5 sheets of 8x10.
There is an index prong that lines up the inner grooves of the two tubes (2840 and 2830) when they are connected together.
Therefore you can easily load an 8x10 sheet and slide it all the way to the bottom and it stays aligned in the grooves.
When using the Jobo processor, it is very easy to lift the assembly by pushing up near the 'heel' of the lift mechanism, and avoid using the lift handle.
The lift handle is, however, convenient to aid in lowering the drum back down, after it is empty.
I just did 4 sheets the other day and results with B&W negative film are excellent. I washed the film in the drum with multiple changes of water.
Though I love my 4x5 expert drum, at this point I see no reason to seek the 8x10 expert drum.