I do and for the same reasons. Quality tends to be superior to UA, especially the seat. It is Polaris all over the long haul fleet as far as I know: direct access. Only drawback: your seat may deflate, but if it does press the maple leaf for a few secs and reset lumbars, works every time.

It is fairly easy to transit. On your way to Asia you won't have to go through security. If doing YYZ it is child's play: there is a transit place where you scan your passport and voila you are on your way to international departures. In YUL it is a bit more complicated because in addition to scanning your passport you also need to speak with Canadian immigration. You won't need to go through security though.

Coming back from Asia is as easy in YUL as in YYZ. There is a place where you sit and wait until your luggage is scanned by US authorities. Then you go through security and then US border (since both airport have preclearance). That means you arrive US side at your arrival, no need to speak to US immigration.

The he only drawback I could see is if you are checking in your commercial material, the immigration authorities scan it and then have questions about it. I believe it would only matter when coming back, and the customs agent after security may ask about it (they have a picture of the scan I assume). When going to Asia, Canadian authorities are just trying to make sure you are just transiting, no question about your luggage at all.

p.s. All considered, this may not be the ideal thread for this question. If a mod wants to split the thread please, with my apologies,