I bought my first mechanical ascenders in 1980. They were Gibbs' Ascenders. I bought 3, and made a "frog-type ascending system. Using single line and ascenders to climb rope revolutionized how I entered the big trees in those days. The frog system worked great, but it could be improved upon, I thought.
Backing up a bit. In 1985 a fellow named "Treeman Jenkins" from Atlanta, Ga. show me the "Ropewalker" system, and by the early 1990s I had a fine tuned ropewalking system just for Moi.
Funny, the only real advances in climbing rope since, for the long straight-up hauls, has been Paul Cox's Raptor.
For arborist work, movement through the tree, friction hitches are far more versatile / efficient, I think.
And for that I've always been a fan of the friction hitch.