Thanks for the response guys,to what extent do you get the substrate on walls and floors spot on,if your tiling a job for a builder or plumber where you're tiling a bathroom and the walls have dips and bellies as such or a floor with the same,as I put my level on the wall to see where I'm going to need to put more adhesive.
from your responses you both seem to have gone back to where you were before you tried them,which is exactly what I'll be doing,as I also find it expensive and more time consuming having to clean off the dried adhesive,as it's easy to clean as you go with standard spacers,cheers Darren.