Well I ordered a Corsair AX850 titanium psu. At first I thought it was 150mm in depth but after It had already shipped I realized it was 170mm when I looked at the seasonic unit. Corsair doesn't list what it's dimension listings are in terms of W/L/H like most other manufacturers or in the exact same order as them, and just has the numbers listed thus my confusion.
Examples listed on each product page
EVGA 850 G2
85mm (H) x 150mm (W) x 180mm (L)
Seasonic Prime ultra titanium
170 mm (L) x 150 mm (W) x 86 mm (H)
170mm x 86mm x 150mm
So a 10mm space savings over the EVGA psu, I guess that will have to do, it seems to fit with the fan but more space would have been really nice.
The AX is a bit overkill to be honest but there are three things you never cheap out on in my experience over the years.
Monitor, PSU and whatever you sit on.
And this seems to be one of the better units you can get, seasonic titanium ultra prime internals, a nicer looking external body over the seasonic unit IMO (and a much better price), and some nice thought out touches like the magnetic name plates so you can change the colour.
Not that the last feature will get any use in the R6 due to the psu basement, or in many other cases these days to be frank. But who knows what the future holds for case design. A 10 year warranty doesn't hurt either.