Good luck with the job and the new bike. £5K, thats not to be sniffed at. I might have something in the pipeline that'll be worth about the same.
As for an extra £800 to get a red / white 750, im not that opposed to the black or blue (in preference order!). Just buying the bike will take me over budget. I just know that if I go for the 6, I'll always regret not going all the way!