I’m getting a new set of wheels for my road bike for Christmas and I’m deciding between the new Ksyrium SL’s or the American Classic 420’s. I’ve been riding a borrowed set of 2003 Ksyriums and think they’re great but I’ve heard some good things about the American Classics as well. I’m looking for a wheelset I can use for every day training but also a little racing as well.
Get the Ksyriums, buy them used, have the bearings looked at and replace of necessary. I have ridden mine for 2 years, they are still as true as the day I bought them. They are stiff, light and Mavic makes spectacular hubs. Google American Classic hub review, might help you make up your mind.
Remember, buy the Ksyriums used, they are great wheels, but maybe not $850 great.