I have run a bit of Ninja and a bit of wax filament through em.
I did have a bit of issues with the ninja when I ran it, but not with the lower enclosure...it was prior to my putting hands on a low-pro feed gear. Still a decent print though, even though it was just some gaskets.
From what I read Filaflex is a tiny bit more stable (in terms of being fed through the machine) than Ninjaflex. I am unfamiliar with TPU.