I believe in wild experimentation, if only because it encourages people to entertain far out but good ideas. I hope Patri Friedman's seasteading project brings some benefit. I doubt they can hurt.
Yet I have pretty strong reservations. For one, I doubt these projects will succeed in their primary goals of creating free societies. As Jason Sorens alludes to, these kind of projects will tend to attract the most socially marginized of libertarians- that is to say, loonies. And there are a lot of libertarian loonies, many of whom have crazy, even repugnant, views (remember the Ron Paul campaign?). I have my doubts that these kind of folks will create a blossoming utopia, even if their actual policy preferences may be closer to mine in many ways than the average American voter. A flourishing and just society requires more than people who distrust government. It requires a certain kind of civic mindedness. Bigotted views like nationalism, homophobia, and xenophobia are socially destructive, whether or not they are specifically carried out in public policy. A lot of libertarians might be afraid to admit it, but it's pretty clear to me that a society with fairly libertarian political institutions filled with vicious homophobes or racists will likely be a less just society than a socially tolerant social democracy.
I also feel that libertarians, and others authentically interested in promoting human flourishing, can do real things to improve the lot of people by being engaged in mainstream society. Radley Balko at Reason has done a great deal to bring to problem of paramilitary police force in the U.S. to light, has exposed corruption in government, and may end up saving an innocent man from death row. There are lot of people who are suffering at the hands of the state, and most of them, at least in the short term, will not benefit from seasteading or the Free State Project. They often can be helped by passionate advocates like Balko.
I feel part of the problem here is that libertarians focus on the issues that their ideology highlights, especially in contrast to other ideologies, such as taxation and regulation (though conservatives tend to support lower taxes, they also tend to support hugely expensive ventures like the Iraq war). But its precicely on areas where there's potential for common ground with others that a lot of progress might be made. There is, for example, the possibility of a growing consensus on drug decriminilization in the U.S. Libertarians can do and have done a lot to bring the horrors of the War on Drugs to light. This is all to say that thoughtful, constructive civic engagement can improve the lives of many people, and this seems like something libertarians ought to be interested in.