If you use say 12mm extension tube, you may still be able to go to 1:3 for bigger stuff. From memory when 68mm kenkos are mounted on the 60mm macro the magnification goes from 1x to 2.5x using the focus ring.
My favourite macro lens for ef is the mpe65mm. Great for close ups, however I do miss not having an infinity focusing macro lens.
here are some shots with mpe65mm on eos 300.
ignore the grain, I pushed fp4125 to 800