The initial claims for Vuichard technique were for recovery from fully developed VRS and stated recovery in tens of feet - then it was touted as recovery from IVRS, please make your minds up.
In fully developed VRS you have little control of the main or tail rotor due to the random variations in thrust available at various positions across the disc so trying to utilise sideslip with maximum power applied isn't going to help and will probably deepen the condition.
If we are talking about IVRS - which I think is valid - then application of power is likely to help re-establish the downward flow of air through the rotor without stalling the inboard section (as the RoD isn't high enough).
The sideslip may help or hinder the recovery because you don't know where the worst part of the downwash is - the assumption is that it is ahead and below but that may not be so in a crosswind situation.
Sorry if you think it is keyboard masturbation Freewheel but some of us think that is the height of idiocy to recommend a technique which the inexperienced might view as a 'magic bullet' for VRS recovery - if they believe the technique is so effective they may well not treat the low speed, high RoD environment with as much respect or caution as they should and subsequently get themselves into big trouble.
Pilots must also understand that SWP is not the same as VRS and using the Vuichard technique in this case will make things much worse.