There are a lot of articles out there on why, if you are an employee, taking shares/options in lieu of cash is a crap shoot. Somewhere there is a good blog about the economic aspects of startups for the typical IT worker (not the founders or VCs) and saying "shares are worthless" is a relatively concise summary of those articles. Most startups fail in some fashion and so cash in the bank is worth more than any percentage of the worthless company.
But I have been a contractor for too long, so my worldview is influenced by that. If you really believe in the company, and want to save it money, then go ahead. And it does depend on the company - I interviewed with a decent company in Cambridge that had an interesting way of compensating the IT staff, in terms of money versus options/equity and overall, it seemed like a well run company with founders who were decent people. The company I worked for, and others I ran into during the first Internet bubble, were run by horrible people out to exploit everyone below them. So it depends on many factors, but if I wasn't 110% sure of the success of the company, I'd prefer money.