The Unicender is a love it or hate it device! The naysayers will tell you the Unicender can 'unclip' off the rope (virtually impossible in our opinion) and that it 'creeps' when there's more than 15 meters of tail in the rope (solved with a quick flick of the wrist).
Witness the Work Climb in the video below performed SRT (Single Rope Technique) by Johno Smith (New Zealand's leading Unicender climber) in a London Plane tree opposite Victoria Park Market in Auckland.
Ascent - no problem. The only 'changeover' is the release and stowing of the hand ascender - Johno doesn't even use a foot loop. Then he's straight into the climb.
Notice how the rope tails through the device as Johno climbs hand-over-hand. Also note the frictionless redirect about two thirds the way through the video.
SRT is not the be all and end all of tree climbing but it works well in this instance - and only with the Unicender!
Thanks to Drew Bristow for the in-tree video footage