I wouldn't argue with Heidi. I've seen her Cher imitation. Though in clips, never seen the full show. She IS Cher (wise cracks and all). I've never heard her sing like Cher, but I'm sure that that is the crux of the show (can't just insult Sonny all the time like the TV show).
Her wit is original and not pre-written as was Cher's for TV. A different talent.

Can you act like the person that you are portraying, and at the same time use the same body languange, voice, and visual looks along with wit? It takes a lot of talent.

I'm just a guitar picker, what do I know about talent?