I had to change the wax seal on a toilet this weekend. I decided to try one of those Sani-Flush waxless seals.
When I put it in place I found that the toilet was up way higher than I thought it should be. I weigh about 160 lbs and there was no way I could compress the seal down enough to get the toilet to the floor. The instructions say that you can draw the toilet down via the johnny bolts, tightening from side to side, but if 160 lbs wasn't enough to get within
1/2" of the floor, I wasn't going to chance it.
I measured the flange and the top is about 9/16" above the tile. With a wax ring I can wiggle and press and get the toilet down to the floor with just my weight, then tighten it down.
There is nothing in the instructions or on-line videos that specifically discuss flanges that are higher then the floor, but all of the photos and videos appear to show flanges that are flush or below the top of the floor.
I can see the advantage of the waxless seal, but they won't work in all situations.