I am stuck on a decision between purchasing a used Canon 20-35 f/2.8L or a new Canon 20-35 f/3.5-4.5 USM. I am leaning toward the "L". However, I have heard numerous times that the 20-35 USM is every bit as good stopped down and I have also seen a number of pros carrying the USM model. I would appreciate subjective opinions from the point of view of esthetics. I am an artist and am concerned as much with the "look" a lens renders as much as I am with lines/mm. Keep in mind I tend to like certain qualities of good older glass. I would highly appreciate advice from people that have hands on experience with both. I already have primes in this range, so please offer advice on the wide angle zooms in question only. Thanks in advance!