Tubeless both mtb and road. I much prefer the tubeless road setup( much lower air pressure, better rides...in degrees) but unfortunately my current wheels are not. As with any job the right tool make anything easier. I mount tires and inflate with CO2, nothing to it and never had an issue with either road or mtb. I also put the sealant in though the valve stem which is WAY easier and WAY less of a mess at least for me.
I will say that a flat is much more time consuming and can be messy, BUT like I said never a flat on the road. I've had trash and ran over a nail and it sealed so I could get home so there is that.
Never had a flat on the road with the tubeless. I have cut a rear tire on the mtb and regardless of tube or not that would not have mattered.
If I could have afforded my current wheels in the tubeless version you can bet I'd own them!
As for what @maelochs
mentions about breaking tire levers, I'm assuming that might be the broken tool you are mentioning, I've heard people talk about his in the past but I've never once encountered a tire that tight, ever! I've surely had some tight ones that need a tire lever to get back on but as a general rule with some work I almost never use tire levers and use my hands.
I will say I've gone to using Conti tires exclusively on my road bikes and generally Schwalbe on my mtb but as I say this my current tires on just plain stock tires that came on my mtb except the front. I mounted something more aggressive on the front.
So...that's my story and I'm sticking to it
SOLEY my experiences on this subject yours may vary