I've found the discontinued version of this lens available for 360$ vs. 500$ for the newer version. My question, is the price difference worth it and does the new lens actually test better than the old? I've been looking for reviews but seem to be finding ones comparing the older version with it's predecessor. If the new version is truly better then I'd not think twice about spending the extra money, but I've seen many times where new doesn't = better.Thanks in advance