I signed up for the 4/5 race (10 miles) and the Masters 35+ (20 miles). The 4/5 race was not a whole lot more than a warmup, with the 10 miles going by in an instant. The entire race was about 25 minutes, and not nearly all of it was high intensity -- average speed was 22.5mph. I ran 3rd to 5th wheel the whole race, until the last lap when a squirrelly rider who I hadn't seen the whole race made a ballistic move up the inside of me, overcooked the turn, slid out on the wet pavement but saved it, and forced me off my line and damn near into the hay bales. I lost 5 or so spots, got some of them back before the finish and came in 7th, happy to be vertical.
The Masters race was a different story. This was my first Masters race, and my goal was to simply not get dropped and hang on for a pack finish. The hammer went down right from the whistle, and it was pegged the whole time. What was amazing was how different the course felt at 26mph average vs 22.5mph. The course had also dried out so that helped -- I've never spent so much time at such extreme lean angles
The sentiment I've heard from others about Masters races being so much better from a bike handling and predictability standpoint couldn't be more true. Whether someone's inside or outside, or against the curb, everyone held there line rock steady. On the flipside I also noticed that, although things were smoother and predictable, guys were far more aggressive about grabbing wheels. Let half a bike length open up in front of you and forget it -- your getting cut off.... albeit smoothly and predictably 
I didn't think about it until driving home, but there were some math facts that stood out to me: the course had six 90 degree corners (not including the 180 degree sweeper), and we did 42 laps, so in total we did 252 90 degree corners at 26mph average in 48 minutes. Seriously fun. We also did 42 x 30 feet = 1260 feet of elevation. As for the race, I ended up stoked to finish 18th out of 35 or so starters. What really got me is that I think I could have had several more spots if I wasn't so intimidated the last few laps. I had opportunities to move up coming into corners, but I didn't take them because I expected that the pace would go nuclear at any moment and I didn't want to lose a wheel to follow. I managed to pass a few guys on the finishing straight with no one coming around me, so all in all I was very happy with the result.