LOL Last Chance to stop me!!!! 100mm Canon L IS macro

OK...my name just came up on the waiting list for the new Canon 100mm Macro L (IS) at my local shop. I have to make a decision in 24 hours or they call the next person on the list. This is your chance to talk me out of it (or tell me go for it). Anyone had a chance to play with one of these yet? Am I better off going with a Sigma 150mm or something else??
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Ro