I do think anyone can give good feedback. While most of what lower-level players (including me) say is gonna be shit since they don't know much, the chances are good for decent feedback to come out of their mouths.
I would definitely have at least one IM+ player at all times to deflect any bad ideas.
Also, anyone who says "Scrap it and start over" should be instantly banned, unless that is the only thing that an IM+ player can think of. Even then, it's probably better to keep it to yourself.