Yep, I think my big trouble is 'can' and 'will'. An engineer, being a full-time employee will come in and kick all sorts of ass, while an advisor may or may not help you make the right decision, make the right connections, etc.
Not saying that it isn't good to give your advisors equity but just wondering if you might be better of hiring great engineers and giving them more equity. Probably need personal experience to figure out the right answer (if there is one).