The person answering questions for Felt on Facebook didn't really understand my question about tire size, but s/he went and asked a production manager who did understand. Bottom line, both the Breed and Broam have the same tire size limitations. The max sizes are 700C x 45mm or 650b x 2.1" (53mm). It's just the Breed comes with 650b wheels and the Broam with 700C wheels.

That's actually pretty sweet. It gives a lot of workable options. Everything pretty much works – from 700x25 road tires on up to 650x53.

And one correction from what I stated in my original post (they changed the specs on the website) – both the Breed and the Broam have 160mm brake rotors on the front and 140mm on the back.