Depends on the depth and curvature of the dent, and the thickness of the metal. Seen it done on a few cars, where some dents popped straight out, but others, due to the shape of the dent, the paint started to crack, so they werent fully removed. The people doing the work also may not be aware of the number of coats of paint/clear on a HD, and you should mention this too.

Kevin from Frasers ( ) gave me a contact that does this type of work, but never got around to contacting him... not sure where the card is now though