I regularly develop 11x14 single sheets in 2840 tubes (the one with the extension on the bottom), 12x20 and 16x20 single sheets get developed in 2500 and 2800 series tubes. I also use 3063 tubes to develop 2-12x20s, one 16x20 or one 20x24. I use D-76 as my go to developer. With D-76, no insert is needed. I have also used D-23 divided without inserts without any problems.
I tried using rollo pyro in a tube, but gave up because of lines (made by the ridges in the tubes) showing up on the negs. To me this wasn't a big deal as I get the results I want from D-76. Sandy King has a method for using pyro in tubes, you should find it in the archives. If you must use pyro, I would try his method. It involves taking the tube off the jobo at regular intervals and rocking the tube from end to end.
I tend to use a lot of developer. 750 ml for 16x20 and 1 ltr for 20x24. The Jobo is set near its slowest speed, I think it works out to about 60 or 70 rpms. (Sorry, I don't remember the exact rpms, I have been using the same setting for years.)
I buy tubes on *-bay. I put in low offers and a couple of times a year I actually win. I have accumulated a lot of tubes this way.
I also run two jobos at a time. I picked up a second one really cheap on *-bay. It took two years to get one really cheap. When you're developing one sheet at a time, it gets pretty boring. Running two at a time, staggering the start time by just over 5 minutes, keeps me jumping.
To further speed things up, I do the minimum wash in the jobo, three quick washes of about 1 minute each. As soon as the last wash is done, the tube comes off the jobo and the next tube goes on. While the new tube is in the 5 minute pre-soak stage, I empty the old tube, soak the film in SS and then put the film in a print/film washer for a complete wash. When the new tube is in the fix stage, the old film gets photo-flo and hung to dry.
Bottom line, I've been developing ULF film in jobo tubes for 5+ years now without any problems, as long as I stick to D-76. But, I like D-76.