My one bit of advice about the FX is:
Ensure you install it correctly as it installs differently than many FFMs. Touch to upper bridge of nose first then pivot down onto mouth and adjust the straps for no leakage. The mask will inflate / grab once it is pressurized further sealing the contours. Once you adjust the straps, you should not have to keep adjusting. Just unclip the bottom clips and you are free.
Best of Luck.