Good question... but it does depend a lot on the aircraft and prop design as to what it will glide like engine on or off. It's up to the pilot, but I believe it's a good thing to experience at least once in your own aircraft to know what it is really like, if you own a small ultralight at least anyway. I wouldn't go advocating it in a 206 or something!! But you'll have to find a CFI to do it with you.
I've had an engine go quiet on me on take off in a Jab, managed to land without any damage, and have landed a few Drifters engine off... engine failures aren't my main concern, it's having a clear spot to put down that is!
I'm all for survival and it's a fact of life if something is going to go wrong, it will go wrong. So being half a step in front of it is a priceless bit of experience. I know people argue the point of experiencing these various things - but that's their skin, not mine!