Lol I've definitely been daydreaming a lot this week... I'm considering signing up for the endurance race event now - not sure if I should step up to 250cc and see what it's like or stick to 125cc and get more practice...
If you want to learn more, stick with the 125cc. You will barely have approached the limits of the bike by Sunday during the course. The course is really about track fundamentals and safety, not going fast.
In my opinion, there are riders on the 250s in the endurance races that really would benefit from staying on the 125s for longer - they're really tentative going into the corners, and the extra HP of the 250 is just masking that by allowing them to accelerate out of the corner faster. While on the 125 I was passing a handful of guys on 250s (to be fair, I was also getting passed by lots of guys on 250s, but that's not unexpected!)