I purchased the SL body for the many wonderful R lenses. I am very please with the body and what it offers for the R lenses. I am a bit old school in that even with sport photography, i do manual and regional focusing pretty successfully . Does the SL offer fast enough autofocusing for sports like basketball to increase my percentages of sharp stop action images? If not, I would just keep doing what i am currently doing. However, I would consider selling my very precious 280mmR f4 to obtain an SL 90- 280 zoom if it was that much more efficient to capture action images more easily. Anyone have any experiences or thoughts about this?