For the tack sharp quality of lens and price difference, I would get the Canon lens.
Through J&R online $434.88 - have purchased from them before - reputable dealer.
http://www.jr.com/JRProductPage.proc...+100MM%2FMACRO
That was a good link to the other thread.
Close call. If the price was significantly different, maybe Tamron. But, its not. The canon lens will be the one to go with.......my opinion. Thanks.
Mark