I had an interesting chat with Setcrete this morning, so I thought I'd throw it in the mix. Although there are a lot of self levelling compounds on the market, the setcrete guy said that the only true SLC, is water, so all the marketed problems need a little help, hence put the screws and rawlplugs to the level you want, and help move the product with a trowel; just don't overwork it, or powder will rise to the top, and give you laitance problems. The SLCs that say you need a covering on them, will take a heavy weight, but not movement, so if you drag something across the room, you'll easily scratch the surface.
