Any question answered...

pft, it's only money. You've got the chance, you'll regret it if you don't. Especially as I have the feeling your going to be riding your Oak a lot more than the Cannondale once it's finished.

The idea is to make an "all weather" fast road bike, and given the British climate you are quite correct in that it's likely to get a lot more use than the "no rain" bike.