I've had a good go with this adhesive today, fitted around 20 m2 of honed slate and used just over 4 bags with a brand new 10mm square notch trowel, back skimming didn't use much adhesive as there was no profile on the stone. The only other gypsum based adhesive I can compare it to is, GBTA from Creative Impressions and I think it is very similar with regards to pot life and open time but, far smoother and easier to trowel. First impressions are very pleasing and I'm sure this is going to be the best adhesive of its type, taking into account value, usability and performance. Good job tilemaster.
Oh, and a big thanks to Lee at tiletown for another hassle free delivery. Top man.