I hear a frequent comment of scratching on glass/ceramic cooktops both induction and resistance. I think it is most often used by the pro gas folks to try to disqualify any form of cooking other than an open fire with cast iron grates. Glass/Ceramic is as hard or harder than any cookware you place on it so it shouldn't ever scratch under normal use as long as it's kept clean. I suppose if one had sand on the cooktop and ground a cast iron skillet into it. I use single edge razor blades on my glass resistance cook top and they never scratch nor has any of my cookware.
Efficiency of induction vs resistance will be somewhat higher. The heat is more focused in the cookware with induction but there is some loss in the electronics and the coils. Of course for the energy you pay for gas is the lowest efficiency. It would be interesting to know what the total efficiency for electric vs gas cooking is taking into account generation and transmission losses. But in the grand scheme of things us home cooks really don't use that much energy to cook no matter the source.
Efficiency of induction vs resistance will be somewhat higher. The heat is more focused in the cookware with induction but there is some loss in the electronics and the coils. Of course for the energy you pay for gas is the lowest efficiency. It would be interesting to know what the total efficiency for electric vs gas cooking is taking into account generation and transmission losses. But in the grand scheme of things us home cooks really don't use that much energy to cook no matter the source.