Mmmhhh, I just changed from a SBD external to the Caterham tank housing/system and that solved some problems. I prefer changing a leaking clutch cylinder (CC oil housing) once a year than using any other external setup. With any other system there are more hoses, cables and therefore possible chances for a failure.
With the SBD system my engine had oil temperature exceeding 130°C very quickly when being kicked. From the day I had the Caterham system temperatures dropped to a healthy 90°-100°. No idea why, we checked everything. Pump was fine, sump was fine, I even had an oil-cooler which I don´t have now.
Friend of mine in a similar car has the same problems with the system.
Just a thought. Been there, would never go back.