On a related "sounds kinda crazy to me" note, about a year and a half ago I tried Ryan's vacuum method in an attempt to achieve a similar "clean out the bad stuff, refill with good stuff" result as yours.
I'm really not sure I can recommend it to just anyone, because you can definitely cause some chaos this way if you just go ahead and ram a vacuum nozzle into the pot, but... Working carefully with a chopstick and gently shuffling stuff towards the vacuum, it turned out to be a decent way to get the fine stuff out with minimal mess. You can lift away tiny particles and dust which would normally just fall back in. As with your attempt, I had no disturbance of roots anywhere I didn't want any. This was on a JWP (a vigorous one with a very tall sacrificial leader), which has gone on to grow well since, no sign of any skipped beats, no problems with winter, good budding in the following spring, great growth this year too.
Mostly non-invasive soil replacement can work!
