If you want to have any impact on politics, you have to be involved in one of the two major parties. Both of them are extremely hostile to libertarianism. Most of us have chosen the GOP because it's the slightly easier route, only because the Republicans at least pretend to be in favor of smaller government, which means they have to at least feign agreement with us on certain issues, and can't attack us as violently as we would be attacked in the Democratic Party. Hence I see absolutely no value whatsoever in switching to the Democratic Party. The Titanic sank and you're talking about switching from a crappy, leaking lifeboat to a floating seat cushion. Could be worse though, the people talking about third parties are planning to tread water till the rescue boats arrive.