There is no increase in rolling resistance. The biggest difference in lowering pressures is increased grip and the fact that the tire conforms to things on the trail with more suppleness which makes for a smoother, faster rides overall.
My bike dropped a pound of unsprung, rotating mass by going tubeless. The bike accelerates faster, handles more nimbly, and is easier to get over obstacles.
No way am I ever going back to tubes.
Those are heavy tubes you were running!
I’m interested in going tubeless once I have a nice set of tubeless ready wheels, but it’s not worth it for me at this point. I have cheap wheels, so upgrading those is a bigger performance priority for me than tubeless. I run low pressures already, if I ran any lower I would be hitting my rim constantly, so there’s no traction advantage. I’m a big guy guy on a hardtail, but I never get flats – really, I bring CO2 and tubes but I end up giving them to other riders who have flats. I can change a dozen tubes in the time that it would take me to set my wheels up for tubeless, so there’s no time savings. I use cheap tubes and don’t flat them, so there’s no dollar savings. And I’m not interested in frigging around with goo!