Lens Help for Night Football

My delima, its getting dark to quickly. I'm shooting High School Football here in Oklahoma with my 1D MK II and my 100-400L 4.5 - 5.6. The shots are great as long as its still daylight, after that even with flash the shots are just OK. My Boss loves the sharp daylight images from the 100-400 but I want to get a 2.8 apature lens for later in the evening. I was zeroing in on the 70-200 Sigma 2.8 HSM. It can be had on e-bay used for about $600 or $900 new. My attention is now swung to the Sigma 120-300 2.8 HSM to give me more power for the longer shots that would be somewhat deminished by the 70-200's focal lenght. The 120-300 is about $1600 used or $2100 new. For users of the 120-300 out there will it be worth the wait to gather more cash or is the 70-200 sufficient. How is the image quality with you experience with the 120-300.

Thanks for you consideration.

The Sigma 120-300 is a great lens for field sports. The 200 is a bit short but will work when the ball is on your half of the field. I'd save my pennies and get the 120-300.

Dean--I don't have an answer for your question but you might want to look at two current threads for more input. The photos in "I have found my calling (MU Football)" were all taken with a 70-200 so that give you some idea of what you can get with that length lens. The other thread is "U-12 Boys Soccer" which also talks about the Sigma 120-300.

Hope that helps.

I've been using my 200 f/1.8. I am close to buying the 400 f/2.8 but don't think f/2.8 would be fast enough for our night games. The last stadium I shot in was very dark. I don't use my flash, I don't even take it. I'm really pushing it at f/1.8.

Thanks for the help and ya Erica I'm very jealous of the 200 1.8 my cash is too low for such a great lens so I'll have to go 2nd choice I'm just trying to make the most of what I have.
Thanks
Dean