I can see the swiftness of the system, the instant adjustability and quick on / off time. I imagine when you're not using the flipline, and you don't want it dangling, you wrap around your waist 3X and clip the tail back into the ascender, yes?
All good, however, the ascender is not backed up. The likelihood of it accidentally opening is remote, but lets say you are spiking up to do a removal, planning to set rope once you get up there. You're not on rope yet, you're not using a saw yet, you're just going up, say, a limbless spar, just spikes and flipline for the time. A momentary slip, the scraping bark opens the cam. We read about you in another section of this website a couple days later.
Hypothetical?, yes. Likely?, no. Possible? We know it's possible. This sort of thing being mebbe a likely reason a lot of climbers poo poo the idea of using ascenders in tree care.
Personally, I love my ascenders and can't imagine my professional life without them. When I demo an ascent with a friction hitch, I get friction, which is great if moving through a crown or on descent, but in going up, it lets me know why so many guys expend so much energy and have such a hard time with the simple footlock technique.
Backing up ascenders is really important, whether on a flipline, or going up a rope. I consider ascenders (most models, but certainly not all makes) fairly bombproof, but 'fairly' isn't 'completely 100%'. Petzl is a great model. Thanks for sharing your flipline system with us.