Tubeless is great if you live somewhere that's really thorny - as I do!
Tried a conversion kit with great success several years ago and for the last what... almost 3 years I reckon, have been using Mavic 819 UST with 100% success (touches wood). I get loads of thorns in my tyres, but with UST I used to pull 'em out then carry on riding, the sealant would squirt out for a second or two then seal the hole. Nowadays I don't even bother pulling them out unless it's a big thorn that sort of "worries away" in the tyre.
I've tried all the other options of tyre liners (nylon and kevlar) even glued 'em together but they still didn't stop the dreaded thorns. Slime, well that was next to useless just as the latex filled tubes were. I can't remember them ever sealing one puncture. I don't know why but the stuff didn't seem to go off and convert to a rubbery compound before the tyre flattened. Maybe it stays in a liquid solution because the deflating inner tube moves and slides against the tyre thus not allowing enough air to the sealant which stops it going off? By the time the air gets there the tyre is flat and half the sealant is sloshing around in your tyre. Anyway, whatever the reason gloop filled inner tubes never worked for me and tubeless does, I've witnessed it first hand.
If thorny tracks are where you ride you can't go wrong with tubeless or a conversion kit. I used to hate it in the depths of Winter having to fix a puncture in the icy, freezing cold rain while the wind was blowing a gale only to get another puncture a few miles later.