I was similarly sceptical, after trying to convert Ritchey rims with a Stans kit. It didn’t really work, it was hard to get the tyres to inflate and then they’d fall off the rims and I’d end up on the floor.
But then I built some new wheels with the superstar sentinel rims (mine weighed 400g each, 21mm internal width). I also bought some ‘tubeless ready’ Conti Protection MK2s.
I fitted the tape and the tubeless valves, started pumping and….nothing. So I ended up with the tyre covered in bubbles (just like I had to when I ‘bodged’ it), still nothing so I gave up and put a tube in. 🙄
However…
I tried again after a few days of the tyre having a 50psi tube in and both tyres went straight up with no fuss whatsoever. I think the bead must have been all wonky from being folded up in the box, so once it had been straightened out by the air pressure in the tube it held air and popped up onto the rim.
I’m still trying to seal the sidewall of one of the tyres, but it’s been much easier than with a conversion.
Edit: all inflation done (or not!) with a track pump.