Ok, here goes. I'll try to keep it short.
First experience with tubeless: went from Open Pro rims running Conti GP4000s tires to a demo set of Ultegra wheels with Hutchison Fusion tires, both 23mm. Night and day difference. I didn't notice it as much going from tubed to tubeless, but when I switched back it felt pretty significant. (EDIT: Key point is that the wheels could have been a big factor as well.)
Fast forward to my Domane. Stock 25mm tires swapped for the identical 25mm tubeless version of that tire. Softened up the ride quite a bit due to lower pressures, but I didn't feel as huge of a difference in rolling resistance. To be fair though, I was recovering from knee surgery when I was first riding the bike and didn't put many miles on the tubed setup before I swapped over.
Now, with almost 2500+ miles on a tubeless setup on the Domane, I've had all of one flat. But I rarely got flats before then. Not really feeling like the initial hassle of setup and sealant, etc. is worth it. Putting a tube in was only slightly more difficult than any tubed tire I've done, but it was much messier.
Long term decision: The current tubeless tires will be swapped for Vittoria Corsa tubed clinchers of the 28mm variety. I will continue to avoid flats the old fashioned way.