My usage would be weddings plus typical insect and floral macro shots.
Of course get the L version if you've got the money the better bokeh & sharpness wide open plus IS for dual-use is a no-brainer, even w/o considering the 5d3/1dx lens groups. The non-L is a good budget macro-only solution esp. when the lens is bought used since it's around for some time, the IS doesn't help much @1:1.
Btw the decisive improvements on the L for me are seldom mentioned - sealing (for outdoor macro against dust) and an extended range limiter over the non-L for *non-macro* range that prevents hunting when shooting portraits, the af speed is mediocre at best (it is a macro lens after all).