Well,

1/60 is the standard base shutter speed, a "sports" shutter is usually higher. 1/60 does have some motion blur to it. I don't think you'll start getting a real strobe effect till probably 1/100, so 1/75 would probably be a safe bet, possibly even 1/90.

I would definitly do some small test shots before the event so you can see what you like. My problem with 1/60 in any fast moving sport type shot is that if you want to pull still images from the action there will be bluring problems in most cases, it can also make slo mo look less appealing sometimes.

Having said all that, you might have a different style than me, and the cool thing about video is that you can shoot how you want and develop your own style, so don't feel that you have to do it all the way I or anyone else does. I would encourage some test shooting though, even if its just you in the backyard play fighting with different shutter speeds, haha, I've done that brother;)

A lot depends on Light source.

Color temperature:
If you know the light source, you can preset exact color temperature on the A1s. 3200K for tungsten if the venue has Tungsten lighting (more likely they will have tungsten) 4800K for florescent lights, 5600k and above if they have daylights as Mercury lamps.
The great thing about this setup is that you can shift according to your taste. If you look in your monitor and want a bit warmer or cooler color, you can adjust precisely. I tend to like warmer colors so shoot 3600K for Tungsten lights.

Shutter speed:
1/60 for most of the part. Make sure they don't have florescent bulbs or Mercury lamps, if set to 1/60 you will get flicker. (If your electricity is 50Hz) Shoot with 1/100. Good to check the monitor.