i am planning to try and get to around 4 or 5 motor racing events throughout the year (hence the 150-500 sigma purchase recently) so the fps may come in handy
For sports the 7D would be the better choice. It's not just the 8 FPS that is the difference, it's the whole AF system. The 7D has it's own dedicated AF processor with more (and cross-type) points. This will really come into play when you are tracking a subject, the 7D does a great job.


