Bob, I think "debating society" vs. "real politics" is too much of a caricature. Yes, there are exclusivist radicals who care too much about exhibiting their self-righteousness and state-hatred and not enough about increasing liberty. But there are also pom-pom reformers who care too much about getting LP members into office and not enough about using all the tools in the electoral/political toolbox to maximally move public policy in a libertarian direction. One of Carl's old essays said "garnering 5-10% of the vote at-large wins nothing". That's nonsense. If we had to choose between 1) winning 5%-10% in many federal elections and 2) winning a dozen seats on city councils and in state legislatures, it's obvious which we should choose. Even if you fantasize not about such smaller offices but about promoting these farm-team Libertarians to Congress, look how much liberty Ron Paul has been able to legislate during a couple decades there. It would take another 20 Ron Pauls before their votes in Congress would even START to move the needle. But if 5%-10% of the vote consistently went for increased economic and civil liberty, then lessarchist voters would be recognized as a crucial swing-voter bloc to which incumbent-party politicians would happily pander. Unfortunately, there are smart reform leaders who see all non-LP politicians as irredeemably evil, and while they don't quite say we need to breed LP congressmen in vitro, they are convinced that Congress will only vote for more liberty when it is 51% controlled by LP members who started their careers getting elected to water board.
So my complaint with Rockbardian/anarchist radicals is not that they want to "debate". My complaint is that they DON'T want to debate. They instead want the LP to be a Rockbardian purity-certifying society, whose sacred scrolls declare it beyond debate that Rockbardian anarchism is the only principled school of libertarianism. They have no qualms about engaging in any kind of retail politics -- as long as it is used to proclaim (rather than question or debate) their purity and their hatred of the state. The votes and dues of other kinds of libertarians are entirely welcome, as long as they genuflect to all the Rockbardian idols, and don't try to make the LP ecumenical towards other schools of libertarianism.
The alternative we reformers need to offer is an LP that is ecumenical towards all the major schools of libertarianism. We need to offer an LP that seeks to unite all the voters who want both more personal liberty and more economic liberty behind the electoral choices that will most move public policy in a libertarian direction. We need to offer an LP that has enough faith in markets and competition to believe that any step toward increased individual choice and responsibility will only build the empirical case for more such steps. We need to offer an LP that has enough intellectual self-confidence and faith in the marketplace of ideas to believe that libertarianism is not a flickering candle that can be extinguished by a stray breath from the impure, but rather is an intellectual bonfire that will set a blaze in the hearts of anyone who wants more liberty, and will suck the oxygen from anyone who wants less.