I’m curious why not the 22mm? I know Crowie uses 19mm front and a 22mm rear. Is it just personal preference? I assume it sits on the rim a little different, and less ground surface area contact in theory may have less rolling resistance? (although some say the opposite, i.e. Hed’s new C2 23mm wider rim idea)
I was advised that 19 is better for the reason you mentioned, less contact with the road. Which means lower rolling resistance and also less chance of flatting.