I managed to get my hands on the ResMed one, and... I managed to actually fall asleep!
Admittedly, only for about an hour and a half in total, and it probably took me about that long to actually fall asleep in the first place (I didn't use it when I first fell asleep because I was feeling unwell, but when I woke up around ~6am I put it on and tried to go back to sleep), but I didn't startle myself awake at any point while using the machine
Nothing especially interesting on the graphs I don't think, it'll be interesting to see what the data looks like after a "proper" sleep rather than just an extended nap.
I'm using the ResMed AirFit N20 mask (i think), which certainly fits me better than the Eson 2 which was too big for me even with the smallest size. The mask isn't super comfortable so I might see if they have any other models available, I've tried the Philips Dreamwear one which sits under your nose rather than on top of it but found that breathing out was too painful/forceful on my ears with that style, so I think I'm probably going to stick with an over-nose one.
Anyway, thanks everyone for your help so far, I'll report back once I've been able to use it for a full night...