Whether or not they have a Black Inc is not relevant. If you are checking for size any CAAD 10 will do. Be careful and honest about flexibility and fitness. There will be a difference in both reach and stack between a 54 cm and 56 cm that could make one uncomfortable and the other better. I am 5'10.5" and ride a 56 cm for two reasons, first, I didn't want to go longer than 110 mm on the stem and second, I am old & fat and lack a bit of flexibility. I know how low I can ride for extended periods, so my saddle to handlebar drop can only be between 7 cm to 8 cm depending on the bars. This way I can ride in the drops when I need to and still be as aero as any old guy can be, but not too high when riding the hoods. You can't always listen to shop sale people and owners, they really want to sell you primarily what they have in the store, LBS in this respect are not like car dealerships, they really need to sell off current inventory first.

One more thing, comfort has much more to do with physiology and less to do with frame size, If your ideal size if a 55 cm the any 54 cm to 56 cm can be fit properly. The differences between a 54 cm and 56 cm in climbing are non-existent if both fit properly and anyone who says different has an agenda.