I am shooting 12x20 until I bought it, I used drum processing exclusively, mostly with Pyrocat-HD (I prefer drum processing). With 8x10 and smaller I had no problems with uneven development or streaking, but with the big negs I did. Tried it several times with different amounts of developer, never did get it exactly right. Ended up buying some concrete mixing trays and use them exclusively for 12x20. Considering the cost of film that size, I went with something I know would work.
Personally I don't have any confidence in myself when it comes to shuffling big sheets of wet film around, so I develop one sheet at a time, less chance I will destroy something that way. I havent tried d76 or any other developer besides for ULF (I want dual usage negs), but I have heard it doesn't have the same streaking problems, etc, that Pyrocat is prone to.
Hope it helps.