Perhaps the sleeves are not "in place of..." but "to secure..." L'Hotellier fittings.
Like John, I've used all three safeties.
Also had an airbrake L'Hotellier fail while inside an LS Sleeve, and it was not noticeable until de-rigging. The cost of that little bugger was quite high, even before the introduction of LS tax.
I found either sleeve better than pins. Believe the LS Sleeve only works on fittings with the ball on the end of a push rod. Does the ASW19 have the ball on top of the rod like the 20?
Does Klaus Wedekind still manufacture and sell the sleeves?
Jim