I used tubes and 35 mm Continental Grand Prix Urban in the last TCR, 28 mm gp4000 in -16 and -17. The 35 was very nice on some of the parcours and on some of the small roads in France, but narrower would have been fine. Might have been slower, as they're not that high end of a tyre, though they too use the Black Chili compound, but can't really tell if there's a difference or blame them*. That was 1,5 years ago though, there's more wide tubeless road tyres now, would be interested in some of those. After that I've only really ridden 47mm or wider tubeless tyres as there hasn't been any road racing.
*Actually I'd probably have won the whole race with faster tyres for sure.