May I ask, what do you feel are limitations using the WMR HMD? I haven't researched WMR much yet, are there motion controllers available for it?
You can check my profile to see if my background provides any validity to what I'm about to share or not. Be advised it takes me months to buy anything because I spend so much time researching the best choice by watching and reading gobs of videos, reviews, media reports, etc (my wife calls me "Monk" of the TV detective series). I will refer to Oculus and Vive products as O/V, and Windows Mixed Reality as WMR. I have owned/used Lenovo Explorer and Samsung Odyssey WMR HMD's. I admit to being a "WMR bigot" and fully expect opposing views from the O/V community. I can provide a lot of history and details related to WMR, but will try and contain myself to answering your question. Having said that, here is some info that may be helpful as you prepare to support 100% of the VR HMD offerings. I recommend this YouTube channel as a starting point for supplemental information: Mixed Reality TV
From my perspective the "limitations" are on the O/V side. They have less per-eye resolution, require extra hardware for positioning, have a more complex and time consuming software setup, have about the same "sweet spot" and FOV as the Samsung Odyssey, have heavier HMD's, and require a higher level of supporting PC hardware. As for content/software, anything available for SteamVR works on WMR, and there is a 3rd party app that allows running Oculus content on WMR. The cost for Oculus and Odyssey is the same: $400, otherwise the "below $300" WMR HMD's are considerably less expensive than O/V options. Both provide 6 degrees of movement. Both have similar controllers in terms of layout/configuration and movement resolution (I don't know if the WMR controllers have vibration motors as I've only used mine for flying AFS2.
There are a plethora of web reviews saying that the Samsung Odyssey is superior to anything from O/V. Search on something like "Oculus vs WMR".
Based on my readings I'm getting about twice the FPS on my punny I5 7600K/GTX 1060 than O/V users are with I7/1070.
But to answer your question, there are no limitations when using WMR vs O/V to fly in ASF2, except maybe the haptic feel. You have done a great job of providing support for 2/3rds of the VR users, now just some minor tweaks are needed to support all of the VR users. I recommend you get a Samsung Odyssey as it has better FOV, sweet spot (focus area), color & intensity, resolution, and ergonomic controllers compared to the Lenovo/HP/Acer/Dell HMD's (which Microsoft provided the template for). If you go for a non-Samsung HMD, I recommend the Lenovo Explorer as it is the lightest and most comfortable of entry level choices. Negatives of the Samsung include the weight and comfort level, and the maker does not recommend using with glasses. I have modded mine to be more comfortable and usable with glasses as documented here.
Let me know if I can provide any additional information that might be helpful.
-=Roy=-