I'm a not so young (70+) amateur arborist, today I purchased a Petzl Chicane from THS and unreservedly recommend this piece of hardware (and additionally, the good service I received from THS).
Previously, when climbing to a height of approx 25-30m on DRT, my energy levels suffered by the time I reached the work area (branch pruning etc) ... with the 'Zigzag +Chicane SRT' combination there's now no need for an aerial nanna-nap before starting work; I'm only expending half the energy to reach the same height. The Chicane-assisted descent was a breeze, the rope 'f'eed' was smooth and easily controllable, even at speed. I have never felt in danger while ascending with the DRT+ZigZag, however, I must admit I have greater peace-of-mind while descending with the Chicane+SRT. Excellent bit of gear; I'm impressed.