I had uneven development when I attempted rotary processing of black and white with a five reel Paterson tank. The reason may have been that the reels weren't turning with the tank, since they're not really attached to one another. I did use lots of developer.
This is a good point that I never thought about when I was scheming to try it myself.
One interesting thing is that Unicolor did make an adjustable reel tank for use on a roller base. It couldn't use Paterson reels however. You had to use special Unicolor reels. One would expect it would work properly.
I ended up with one in an eBay auction bidding on an 8x10 tank to use for sheet film. Took a few minutes to figure out how it works, but I never actually tried it. It's stuck in a corner somewhere.