After having tried the Canon mk3 1.4 extender paired with my 70-200 f2.8 for football and not being impressed at all, Im going to go for a 300mm f2.8, and the cost of the IS version is a lot higher than the non IS version. Given that I will be using the lens with an R6 or R7 which have built in IS, would it be a waste of money going the extra cash for the IS version. This will be mostly used for sports and Ive read a good few times that IS is not recomended for sports? Can some of you more experienced kind people help with some good advice please?