I've run Barlow Pass EL with and without tubes and can't tell much (if any) difference.
For the wider tires (44 mm, 48mm, 55 mm), I have never tried with tubes. I imagine I would feel more of a difference.
I think their official advice is not to run anything narrow than 35mm tubeless.
IIRC, Jan says tubeless setups with their tires are marginally slower.