I chose to buy the Bullitt calipers seperately because I wanted a drilled rotor. I bought the calipers from PPI since they had good service and were willing to ship via USPS (which doesn't cost a kidney to do so to Hawaii), SS lines, Hawk HPS brake pads (big mistake), and genuine Brembo rotors from Tire Rack ($$).
The HPS pads squealed like mad, and nothing I could do nor my friend's shop could do would get rid of the noise. Ended up ditching them into the trash can and replaced them with the OEM pad that came with the caliper, and poof, noise gone.
The SS lines made a HUGE difference in stopping/pedal feel. Make sure you get a set.
I bought the Brembos because of the name, basically. They were costly for sure, but the are holding up well and the although the coating has worn off on the parts that the pads make contact with (duh), the rest of the rotor still looks great. IMO, buy a zinc coated rotor if you can afford the extra bucks.
If you buy the Cobra kit for the rear, you do have to remove the axles. It's all spelled out in the installation instructions I found somewhere (if I think of it I'll post the link), so that may be out of the question for you. I still want to upgrade the rears since the 10" rotor looks way out of place now with the 13" one in the front. Plus, one caliper is red and one is silver now (ugh). You may just find that the upgrade of the front is enough for you.
BTW, although it states that the Baers come with that warranty, be sure you know the exact coverage before you buy them. There is a cute little * asterisk at the end of the sentence stating the warranty on the Baer page.