-
Pardon the slow reply to the concrete question., I was driving to Exmoor. Tiles are not famed for their bendy properties and if they aren't perfectly aligned at every corner they look bloody awful. Thus, the slightest ridge in the concrete of even 1mm will bugger the entire surface. If the ridge hasn't been spotted it is evil incarnate to attempt to make the tiles match up and the whole lot might have to be lifted, probably sacrificing any tiles that have already been laid. The adhesive goes off in minutes and makes shit to a blanket look an insecure bond.
You can get away with slight deviations with stone, particularly when using a 25mm bed of mortar, but anything ceramic is unforgiving.
Pros:
Cons:
So pretty lucky overall.