Well, the project truck I've got now has an nv4500 in it. Nv4500s and I don't get along too well, as while I had that version of transmission in my old cummins dually, I broke about ten of them.. It got expensive rebuilding them after I'd go out and play a little and pop! Something would break.
I had a g56 in my 08 6.7 cummins, I really liked it but the "gear roll" drove me nuts.. Did an auto swap, it broke, then threw in another nv4500, but didn't like the gear split between 3 and 4th gears, so found an nv5600 and threw it in. It held 630hp just fine, but trying to shift that thing fast, hahaha yeah right! I had better luck with the g56, and I've found a couple that are better priced than what I've seen the zf's go for. Don't get me wrong, if I find a zf that's affordable I'd jump all over it... It's just easier to find the dodge stuff than the GM stuff as they were more rare..
On a side note, speaking of a zf, how well do the ford zf's hold up?