I certainly wouldn't size down. My 60cm CC already has a lot of post showing. That combined with the short head tube make for an odd looking bike. I have a longish pubic bone height--90.5cm--for my height--6'.
Yeah, so sizing totally depends on your riding goals. Are you going to ride road/cx style drops, dirt drops, flat bar, or alternative (mary, loop, etc)? How do you have the cockpit setup on your CC? At only 6' tall, the 60 seems very large, but if that's what you're used to and that's what you like, go for it.
Not to turn you away from the Straggler, but maybe take a look at the Singular Peregrine. It has a 59cm TT and 61cm ST. On paper it looks like a mix between the Gen 1 Fargo and Straggler, given its larger tire clearance. The All-city Macho Man disc has 60.5cm ST and 58.5 cm TT -- possibly an ideal fit for your body type, if you're after a more traditional cx like the CC.
I'm coming off a Gen1 Fargo (non-sus corrected), set up with Woodchippers, which I never got comfortable with. It road great off-road, very much like an XC MTB. However, it was just painfully sluggish for me to put in long road miles, to commute or tour on. I'm looking forward to the Straggler as my CX bike, which should fit (IMHO) similar to a standard road bike, but the geometry should have more stability and better off-road manners.
Good luck!