erm... i think ill go for the upgrade and see how the car copes.
the issue with the rear convo is that someone said it might affect the braking balance. personally i think that would only play a part if both rear and front had same size discs (and ie. the same stopping power) . im pretty sure the setup is designed to have larger braking emphasis on the front... i.e. discs more powerful than drums, and therefore large discs on front to std 239mm on back shouldnt affect the balance too much.... (thats my theory anyway)
am tempted by the rear axle in the parts for sale, but not sure how much linking up would be. not a diy person, so it would have to be done by a garage...