Many thanks to everyone who gave meadvice regarding my dilemma.
There was a lot of posts saying to get the 7D, and then with the spare cashupgrade my Lens (Canon 300L F4).
Well yesterdayI purchased a second-hand Canon 500L F4, and have decided to stick with my 40D camera for the meantime.
Look out for posts soon about what Gimbal head / tripod combinationworks best!
thanks again,
John.