What is a recommended height for tile edging?
With larger tile that may span irregularities, I would advise 1/16 higher to end up flush.

With mosaics, I would go for the same height.  Too much thinset with mosaics makes a grout line mess, oozing up and needing extra cleaning.  

If you are using unbacked glass mosaics, be sure to skim coat the whole field with a white thinset before pulling.a notched trowel for the final setting bed. Then flatten the ridges for a smooth, void free bed that won't show variations through the glass