Bring it... even if you don't use it (which I think you will), it's like a condom... better to have one and not need it than need it and not have one... lol. At worst, attach a string to it and sling it over your shoulder when you are not needing it, but want it close.
Five points:
- Check your white balance OFTEN or shoot in RAW and relax/forget about it.
- Use fast glass and crank the ISO and go for at least 1/320th or 1/500th and faster shutter speeds.
- For longer areas of movement (where the athletes will cover larger areas like floor exercises), set focus to continual, otherwise single focus for other areas.
- Use center weighted exposure, seems to work better for my D200 and D700 in these kinds of situations. Don't be afraid to change the fixed location of the focus points based on whatever composition you want to accomplish.
- Leave the flash at home. The last thing you want to do is blind an athlete as they are half way through a rotation and 6 feet in the air (bet you knew that one.... lol).