i want to upgrade my rear derailleur from a tiagra to a dura ace. and possibly the front as well. my shifters are tiagra. will there be much performance improvement or just abetter quality product with less chance of breaking. also the rear derailleur looks like it has less chain clearance so would i have to take links out of my chain, and would i also need to upgrade my hsifters as well. explanations are always appreciated thanks