I like your implementation of FluidSync which on my Reverb G2 works well (game fps locked at 45fps).
One question: Have you considered a 30fps FluidSync (i.e. 1/3 of native WMR headset refresh rate?). I think few games would benefit from this as the 30fps FluidSync could make it possible to have them run in Geometry3D (which is, in my opinion, a better option to Z3D).
I am aware that SteamVR + WMR is not able of that (yet?), though the OpenXR is able to reproject from 30fps quite nicely.
That actually existed while developing the feature, but I ditched it in the end. Don’t really know why anymore, and I think it’s a good idea. Unless there is some technical reason preventing it, I’ll add that for the next update. I.e. no promises, but 90% sure that it will be implemented.