Canon EF 70-200 f/4L USM

I am looking to buy the Canon EF 70-200mm f/4L USM, and am looking for any advice on weather or not I should bite the bullet. For the past 8+ years I have been using the Canon EF 75-300 4-5.6 III USM and have a T2i. I take photos for fun, and am mostly interested in improving my son's baseball photos. The IS lens is more than I am looking to spend. Could the L lens make enough of a difference to justify the purchase? Thanks for any thoughts.