Topping up, reseating? My experience with tubeless (on a mountain bike) is that I buy a new set of tires, pour some sealant in (Stan's NoTubes), put them on a bike and then ride until there's no tread left. I don't think I've ever had the sealant dry up. And that's with a regular rim meant to be used with tubes, converted to tubeless with an aftermarket kit.

I agree with having to carry a tube or two in case the tire fails catastrophically, but other than that I consider tubeless bulletproof. No experience with touring though.