I feel like a lot of great companies would never have been built if the founders didn't ignore a bunch of naysayers. That said, if you get your product into users' hands early and often and nothing you do can persuade anybody to like it, you're probably better off not wasting any more time on it.

5) The fewer heads, the better

I'm going to have to agree with pg and say that going it alone is a bad idea. You need multiple, complementary skill sets. You need to balance out mood swings. You need varied backgrounds and bodies of experience to provide multiple perspectives on all the problems you'll undoubtedly face.

However, I can totally relate to the author when he says, "On many occasions, I’d come up with a new, inspiring idea, only to get a knot in my stomach before pitching it to my team."

I think it's important to cultivate a culture where it's perfectly acceptable to throw crazy ideas on the table and get them shot down. In fact, I think the more ideas you can burn through, the better. Creativity is an iterative process. Often times your crazy, will-never-work idea will spark a brilliant idea in the mind of one of your cofounders.

On a related note, we've found that getting a 3 person consensus on everything is a broken model. For any given decision there should be exactly one person responsible for making it. You can either divide up the problem space or you can just defer to the same person on everything. We even decided to rotate who gets to wear that hat every 4 months, to give everyone a chance and to make sure we don't stagnate.