I've used the 400 a bit, and have some more in the fridge. I don't have much problem with the curling. I use Jobo reels which, IMNSHO, are far easier to load than steel anyway, and put the negatives into neg pages (for 120.)
I like it in 120 and 4x5 - quite a lot in 4x5. I shoot mainly TMY-2 in 4x5 but the Foma (and this stuff is just re-branded Foma) has a different look that I also enjoy. It's far grainier, but that doesn't matter at all to me in 4x5 where I never print larger than 16x20, maybe 5x with some cropping. In 120 I don't mind, and in fact it's nice to get some visible grain at sizes where even Tri-X will not show any.
I don't understand the argument about cheaper in 35mm, though. In 120 and 4x5, yes, but you have to be getting this from Freestyle to get the Arista brand, and for just a few cents more you can get re-branded Tri-X in their Arista Premium. Sure, a 100' roll is ten bucks more but that's still a pretty good deal. I don't see the point in bulk loading it unless you want shorter custom lengths, given how cheap the 36x loads are. 36x loads of Arista Premium aka Tri-X are $2.89. The Arista.edu Ultra aka Fomapan 100 is $2.59, 400 is $2.69. If you want inexpensive film in 35mm without QC or curl problems, just use that. Of course you're stuck with 400 speed now that Plus-X is sadly gone.