I am just back from the watchsmith.
My SMP Chrono was tested 100m 330ft waterproof - even though the pusher are not screwable.
He only has got such a vacuum test device which goes to 100m, so the watch might even go deeper but 100m is good enough for me.
I had a cup of tea and we took the time to leave it in the vaccum...so it withstand abaout half an hour!
AND: there is only one place I have read about the screwed pushers. Maybe its a wrong info? But why would Omega put a fake "nut" (? hos is it calles?) on the pusher?