"Peter, What rims are you running the Calypso on and how hard are they to get on and off?"
I've got them on MA2's, MA3's, Mavic Open Pro's, and Campy Omega 19's, and they've been a one-tire-lever fit -- use one tire lever to quickly zip them off the rim. I put them on easily with fingers only. No issues. Tighter than Vittoria Opens, which lift off with fingers only, but not tight enough to ever be a problem. A bit looser than Contis. Seem to have good flat resistance.
By the way, I just put a tape on one, and it's not 25mm, as I said it was. A bit less.
pb