i don't think that Tom was advocating spurs; just commenting on spurless strategies.
i've had a footlocking injury a number of years ago; but that didn't lead me to using spurs on trimming. For, the truth has leaked out; wearing spurs on trims does damage to the tree that you say you are helping. Many times in trees with good CODIT responses, the spur damage outlast the damage of properly made cuts. After all, a proper cut tries not to harm the parent that the spurs are tearing up, and also tries not to make torn fibers in the cut, that the spurs make in said parent; all the way up to the cut.
i was always frustrated with speed etc. on foot locking. The one time i thought i was getting it; i ended up in the emergency room the next day, after frantically going to chiropractor and regular doctor, then deciding i should go into the emergency room. i had partially popped my hip out the day before they said. i passed out from the pain soon after getting there and telling them i was going into shock during the paperwork.
i had been lifting my legs up extra far the day before, almost to a yoga type position; knees out to side, with soles facing each other, to get extra length with each thrust up. Mostly to make up for my short legs that the strategy uses for ascending(legs are so short; that when i stand they barely reach the ground). When footlocking, knees should stay over feets; not leveraged to side!
i might footlock 15-20' anymore when in tree (rarely). For ascending; i go with Pantin, and Kong double handled ascender; that pushes a modification of the self tending Sailor's Gripping Hitch up, as a prussik type safety grab to second the Kong's cam; as SRT (Single Rope Tom) recommends. Pantin being a great help to ascend, but not a real 'countable' safety grab on rope.
So, that is my take on both sides of the issue going spurless, and footlocking. It has been tough sometimes; but right is right, and spurs are wrong on trims.