Well after a lot of soul searching...Martin (user Mill) gave me a Texas Instruments
PTN78020WAH adjustable switching regulator to try/use.
This item is excellent and can supply up to 6 amps! I made up a small cct board (with eagle) and am running this at 1amp constant (to simulate the camera) and there is virtually no heat emitted from the regulator....aka it is efficient and damn stable.
In fact there is a quantum more heat dissipated in my load testing resistors, which was not the case with the old adjustable linear regulator I was trying!
These new switching regulators have much more inbuilt protection features than I could add to a std linear regulator so it's basically add a few resistors & capacitors & away you go.
So it's all going in a small box and will be powering my 450D soon.
I'll report back on how this progress but I must say a big thanks to martin for pointing me in this direction.
