I know you frisbee golfers are a pretty active group, so I would think that Size and weight is important to you.
The above two lights are great, I own two of the Surge's. Great light, but it takes 8 AA batteries.
Also, that SL6, with it's very narrow, bright beam might be exactly what you want. That pencil thin, narrow beam for spotting your frisbee's.
Also, I would have to say look at the SureFire M3 or M4, or maybe one of the rechargable SureFire's.
Go to
www.brightguy.com and look up SureFire, or go to
www.surfire.com . There are lots of options for lights, but I am thinking that you want lightweight, right?
These lights are designed for high output, and light weigh carry, but are expensive!
Now, are you using golf carts?
If you were using Golf Carts, it is a whole other story, get an Optronics 2 mil CP spotlight for like 50-60 bucks. Blows any other suggestion here away, but is heavy and has like a 30-40 minute run time. You can even buy extra batteries, and charge up several of them at a time.
http://www.cabelas.com/ has them.