I've been using tubeless road tires since 2011.
Shimano rims with Hutchinson tubeless fusion tires and Stan's sealant.
I use this tubeless setup on races and Brevets.
Without an escort on a race if I get a flat I'm finished. Flatting with tubeless is less likely. I have never flatted on a race with tubeless.
I used race 5 times a year. Now I'm down to 2.
I used tubeless on Brevets because I hate repairing a flat in the cold, rain or at night.
In all these years most of the small holes self-sealed themselves. In one occasion it didn't because of insufficient sealant (my fault).
Most of my flats were from tire slits either in the sidewall or tread. I don't know if they could all be repaired with a plug, but in my case I added a boot and inner tube which was a hassle.
The valve needs a small leatherman type pliers to unscrew because it's been tightened not to leak, and cannot be unscrewed by hand.
The sealant is a mess, and usually the tubeless tire is difficult to mount with a tube.
It's definitely more involved than replacing an inner tube.
I have no experience using a plug, but I'm going to try it in the future.
My latest flat was caused by corrosion around the valve hole that the sealant could seal; a plug wouldn't have helped.
Stan's sealant definitely corrodes Shimano rims, even the ones with the new alloy.
Stan says its sealant is non-corrosive, and that the alloy is at fault, and Shimano says the sealant is corrosive. The fact is the rims corrode.
The other problem is when you remove the tires from the rim to clean the setup that I do once a year it is very difficult to re-seal the used tire back on the rim even using a compressor. Sometimes I have to replace the tire with a new one even though the used one is not worn.
I don't know if this is due to the combination of tires to specific rim that I'm using.
Maybe, using a pump with an air cylinder would solve this problem.
If the cleaning would coincide with replacing the tires for wear this would not be a problem. So maybe, I should have using the tubeless setup consistently.
Since my races have dwindled down to 2 per year, and my Brevets are less than 300k, and the weather has to be decent maybe it's an overkill using tubeless road tires.
Also, I think that the quality of the regular road tires has improved over the years. I don't seem to be getting many flats even though the roads are deteriorating.
I will definitely continue using tubeless tires on my Mtn bike.
So I am still in a dilemma.