It would open doors to opportunities, whether the start up succeeds or not, if you make enough contribution to that start up to get noticed by insiders and outsiders. Of course, you got to do your part to make sure that others notice your contribution too.<p>Also, how valuable you are percieved by later employers also depends on how much you learn from that expereince in that start up.<p>Two people who have gone through exactly the same experiences may end up coming out of it wiser at different levels.<p>How much you learn would depend on how much observant you are on what goes on in the start up, what works, what doesn't work, and in what circumstances something works or doesn't work.<p>All this is 'experience' you can leverage and it needn't be limited to just the engineering stuff.<p>I worked as a project engineer in a small company earlier, which wasn't a start up, but had lots of similar characteristics. I learnt a lot not just on the technical side, but the business side as well, dealing with suppliers, pricing, setting up a supply chain across two countries, training others, because we were expected to be jack of all trades.<p>All that cross functional experience helped me land a job in much larger company as well.<p>Good Luck.