Wanted to bump this thread as I love my Fujifilm X-T1 for topside use, and really want to move to the NA-XT1 housing to replace my Sony RX100II setup. I've got the X-T1, 10-24mm f4 and would buy the Zeiss touit macro if I went with the X-T1 for underwater use.
I'm a big fan of the colour rendition of the Fujifilm, far more so than Sony. I've also looked at the Olympus EM5 MkII setup, purely for underwater use, but that seems overkill given I wouldn't want to replace my Fujifilm gear with it for use topside. Final alternative is sell off my Nikon D700 system (no housing, only used topside), my Fujifilm X-T1 setup and go all in on Sony A7II or A7RII, for both UW and topside use, but I'm wary of the extra size the Sony system brings with a decent increase in lens size, if not body, over the Fujifilm system.
My main concern in going with Nauticam and the X-T1 is there's zero feedback anywhere on it, good bad or otherwise. I was talking with the Australian distributor of Nauticam a couple of weeks ago (when I upgraded to dual Z240s for my RX100II rig), and he said he hadn't sold a single NA-XT1 housing. It's pretty clear to me there's never going to be an upgrade pathway from Nauticam for the X-T2 (or X-T1 MkII), based on the very low take-up of the NA-XT1. It seems like the N85 port system has widespread use across Sony E mount, M43rds, Canon EOS-M and Nikon CX mirrorless lines, which may give options for using a future Fujinon fisheye I guess..
Would it be a huge mistake to go with the unloved, unknown X-T1 Nauticam setup?