I suggested last year at several contests to hold the Freestyle Saturday evening. That way, people can still leave at a decent time on Sunday. I dont know a single contest that I have ever been to where we flew IMAC rounds till dark on Saturday.
Do it then, everyone is still there.

My personal thoughts on flying freestyle are pretty much what Daniel said.
But I will add this, its VERY hard to come up with a truly good freestyle routine. I just dont have the time to go to the field and work on that and not focus on precision.

I had a decent routine in 04 that I flew at the XFC and did pretty well with.
I used that same routine at a few IMAC's and found I was getting beat by guys flipping and floppin over the runway for 4 minutes with music playing in the background. It got old and I havent flown Freestyle since. Sour grapes? Probably.