h.c.e.
Power User
200ms is fine, Ultra-Res IR is 170ms/48kI got a pack of them, not liking the thing too much, for the Axe FX III do you download the labeled as "Fractal" or make a custom 48KHz 500ms? the default for Fractal according to their page is 200ms.
https://wiki.fractalaudio.com/axefx2/index.php?title=Impulse_responses_(IR)