[PDUB]

...like any engineering solution, there are tradeoffs. As you point out, working on the rear brakes of the original Jag setup is horrible at best, even with a lift. Many here can chime in with support on that. Access is bad, period; a hatch helps some. The brakes do not cool as well in a performance application. They are subject to oil leaks under the car, etc. Its real advantage is unsprung weight, which improves ride and handling.

An outboard brake setup is original to the production Cobra. Cooling is better, and you have the option of vented rotors. I think the rotors are larger with better calipers. There is less likelihood that leaking oils will foul the pads/rotors. The parking brake design is improved. You could even implement the anti-lock feature if you were really industrious; read . Torsional loads are about the same, either way, as you have acceleration and braking. And when it comes to servicing them, no comparison - outboard baby!!

Performance wise, the outboard system has the edge with better cooling larger vented rotors/calipers. Others will add their thoughts... and clarifications.