My only problem with the 520 is the weight,I will probably put 700c wheels on the Cannondale f2000sl,this will be cheaper anyhow.
I'm not familiar with the Cannondale f2000sl but what size wheels does it come with? You can't just put 700c wheels on a bike with "26" wheels(ISO 559)because the brakes (cantilever, caliper or V-brakes) won't line up with the rims.
If it has disc brakes you could lace 700c rims to the existing hubs but that won't be cheap and you have to be sure the fork and frame clearances are sufficient.
I think you are making too much of an issue about the 520's weight. If you don't need them, take off the racks and it will be at least a kilo lighter.