You must enjoy camping Cheesewheel

... if you get a puncture that doesn't seal itself then you have to fit a tube... can be a bit messy, maybe a tight fit, that's the only difference from a standard tyre.
Sealant on the drive chain being a problem ?... it isn't going to happen.
rifraf, there is a giant thread on tubeless somewhere on here... personally I was one of the first to try it because in Sydney I got sick of punctures, thats about 6 years ago now so the tech isn't that new. It worked well, would have been less hassle on tubeless specific rims as I did need a CO2 can for the first inflation, but apart from that it was great.
But since moving to France I only get one or two punctures a year, I can handle a puncture every 8,000kms or so. So I don't bother with tubeless anymore on my road bike. I change tyres often as I like racing on newish tyres, plus I can't be bother setting it up on a 50 or 80 mm wheel. MTB without question tubeless. I tried tubeless on my cross bike ( same wheels as roadie ) but didn't have much luck with it. But I may try again if I get tubeless specific wheels and tubeless cross tyres... but they aren't very common or all that good at the moment.