Ace Races are a ton of fun. I like feeling like my opinion counts towards a prototype's future. The group of discers that you play with makes all the difference... if your big group of friends are doing the Ace Race and they all live 3 hours away I'd say it is totally worth it. If you don't know anyone there it might not be as worth it. Usually there are other unofficial festivities after the Ace Race that might make the offer more tempting. I wish I had done it the years they did the Meteor and the Impact... 2 ESP discs, a hat and other stuff for $25 is not bad at all.
The winner gets a huge bag full o' discs... I was lusting when the winner was going through his bag; "XL, Avenger SS, Predator, Meteor... who throws these things?" I do! Give them to me!