LF...We have a glass top (smooth)
I keep a black iron skillet on it at all times.
It has never scratched it. As a matter of fact I dropped the skillet on it from about a foot and it didnt break the top.....Nancy however almost broke my head.
It sounds like we have about the same unit as Ray...Sears.
It takes the smooth top burners longer to heat up, longer to cool down and is harder to regulate than our previous electric stove with regular coil elements. It is easier to keep clean, we use the ceramic cleaner made to clean smooth tops with....and after 3 years the stove looks new.

[This message has been edited by Buzz (edited 23 February 2006).]