Look, even if you have an ailing clutch, and you had to use this technique to preserve it, wouldn't you also be destroying your gearbox? I find it surprising that the car did not stall since it went into quite a low RPM. I always thought it was impossible to shift gears without a clutch. I'm not going to be foolish enough to attempt this. If any of you are going to try, all I can say is "do everything to maintain your vehicle."