Overlay UFH

Has anyone had a system they've tiled straight on to and been happy with?

We've had the original polypipe overlay at a different house with the heavy gypsum type boards and a couple of the tiles cracked.

We've just had a quote from wunda, the rapid boards are quite lightweight and made out of foam but are approved to tile onto. I can't help but think we are more likely to to crack tiles on this than the gypsum / fibre boards.

Thanks