Nope I had not heard of that method. I was aware of some mip map related approximations being used for ambient occlusion calculations but looks interesting. Will have to give it a good read later.
edit first reaction is that it seems like the gains only really showed up with really tall height ratio scales. But they were comparing to relaxed cone step mapping which is already another method that is probably a bit faster. Actually I am not 100% sure which method of pom they were comparing against in the performance chart. I will probably try it since it doesn’t seem that hard to do.