Honnestly, if by mistake you blow inside the Ascent instead of sucking, yes, some vapor can escape by the bottom, but it's the same vapor you would exhale anyways...
I'm able to use the Ascent at the office, windows closed and most of the time nobody even notice. And outdoors unless you stand under 1m away from me precisely when I exhale, there's no chance you can spot what I'm doing.
In fact, it smells way more when I open the jar to fill the bowl...there's no perfect stealth device, the herbs we use are definitely smelly.
That being said, convection vapes like the FF or FW tend to smell less, the Ascent would be closer to the Pax yes. Being mostly conduction, if you let it cook for some time, vapor builds up and can start leaking. You're not supposed to let it cook alone for too long though, battery life being pretty limited on these portable devices (plus the fact that the longer you wait the more they get hot, and the more it damages the batteries) so even if they can do long sessions fine, they tend to force you to shorten them and consume at a faster pace.