Just be careful you do not go overboard with modding up a Corbier, because to cost of the components can easily overtake the value of the entry level bike....
I'd just keep the mods to just the wheels (aluminum rims) tires (High pressure/narrower/lighter) and the shifters (Clamp-on, Down tube) and just tune the existing brakeset to make it work best.
Anything over that might justify just buying a better whole bike with all the goodies on it already.....