Many say that if you use an high quality “open tubular” clincher tyre and a latex inner tube on a wide clincher rim you get equivalent ride quality to a tubular tyre. I tried it; it is in no way equivalent.
I used Vittoria latex tubes, Veloflex Corsa 23 tyres, and a pair of wheels built with Flo 30 rims & veloplugs in lieu of rim tape. I inflated them both to 120PSI (the low end of what I use with my Vittoria Corsa 23 tubulars). It’s possible that the Vittoria Open Corsa would be different, but I doubt it: the casing is the same 320 TPI CoreSpun and the tread and construction are almost identical.
The traction and lateral grip are there, but the comfort isn’t; it’s like riding the tubulars at the 145PSI I use for racing. It’s possible that reducing the pressure would improve matters but given that the tyre is held onto the rim by that air pressure I am rather reluctant to drop it. I am also unable to go to 145PSI for race day because of the danger of blowing the bead off the rim.
The comfort is perhaps very slightly better than a Conti GP4000S clincher, but not sufficiently so to forego the improved aerodynamics from using the tyre the rims were designed for: there is an obviously smoother transition from tyre to rim on my wife’s GP4000S-wrapped wheelset. When these tyres wear out I will replace them with a brace of Conti’s.