Hmm interesting question. I suppose there is no need to restrict but I would say that as great as Woz is - would he really add more to your startup than an angel investing veteran like Ron Conway? Investing is as much about bringing a list of contacts to the table as it is about anything else.
It's more about street cred than anything else. I want an investor who will make people think "if he's putting his money into this company, it's worth checking out". A knowledgable VC can bring me to other investors/acquirers. Someone like Woz could bring other investors to me.
