Hi Only,
While the solid opps is a long awaited and valuable tool I try to keep my actions the simplest method possible as often as possible. In that way to place a circular hole in a slab I would have stuck with your ver 6, magic wand method. Place a circle where you want it on the slab, with the slab selected and the slab tool active, click on the edge of the slab, select the subtraction action from the pet palette, then magic wand inside of the circle, bingo!
The thing is no extra layers to shuffle, hide, or objects to accidentley modify or worse delete.