I use the technique with the frog ascent for a floating false crotch to work the tree on the way up or undertake aerial rescue (clip a pulley to the butterfly and run DdRT system). You can also just clip the end of your work line to the butterfly and enjoy a third back up from your friction hitch/rocker type device if going straight for the top.
Been practicing with various endless loop configurations to allow only 2xH for access line, as Mark shared in the killer bees thread.
This technique solves security issues by using ascenders on kernmantle rope for one person loads while ascending (their design intention), and knots and DdRT for a floating false crotch and anchoring two persons in aerial rescue. No need to fear the extra weight of the casualty should it be required mid rescue (should you find the casualty has a cut/stuck/short line) because the rescuer isn't belayed off ascenders. Just put a fig 8 decender or meunter hitch under your hitch to help with the increased load.
In a work situation, it also means you can work the tree on the way up anchored off a knot rather than a friction hitch or ascender of a typical FFC. It uses ascent systems for ascent and work positioning systems for work positioning.
If there isn't much branch walking involved, I'll just run a standard Frog and switch to a Gri-gri to work from, then run a RAD set up for short distances between branches, or clip back on the Frog to blast longer distances with ergonomic speed and ease.
Being more efficient with energy and safety systems certainly makes tree work more enjoyable for me. I'd recommend this approach to anyone.
