I am looking to get into macro photography, flowers and insects and all that good stuff. My next lens may be one of these, I can't decide which though. I already own the EF-S 60mm Macro, but want something with more working distance. Does anyone own either the 180mm or 100mm IS macros? If so whats your impressions of them. The reviews seem good for both, and I probably couldn't go wrong with either. Do you macro guys feel that the extra working distance of the 180mm is really important?