Tubeless riders are still in the small minority on the brevets I ride. I don't get enough flats and have too many wheelsets to make it worth the extra effort and expense.
I thought this was funny from Grant Petersen in the Rivendell email a few weeks ago:
I just learned about DynaPlugs the other day and I'll pick up a set of those. I'm not as wary of tubeless as I used to be, but it does seem like it solves some problems only to create others. The net problems solved is zero, they're just a different set of problems.