I think the way to go for a most startups, save the likes of Amazon and Ebay, is a small quiet and private launch during which their product can be refined and

I think the way to go for a most startups, save the likes of Amazon and Ebay, is a small quiet and private launch during which their product can be refined and tested. It's easier to handle feedback from small number of, mostly, tech savvy users than from tens of thousands of, mostly, non-tech savvy users. And the feedback would be of greater quality. Launch PR can always be done afterward, say when the site moved from private Beta, when the product is worth hyping up, by then the tech savvy won't give too much criticism.