Which Section To Play In at Monument Open?

The Monument Open is being held next weekend here in Colorado at the Sundance Lodge in Monument. I played recently in the Pikes Peak Open two weeks ago in Manitou Springs, Colorado and it had only one Open section for all at that time. I was paired with folks much higher than me and learned a whole lot, although I did not qualify for any prize money. I was able to get very playable positions even against Experts but made small, but significant, errors in the middlegame which cost me some wins. I did win against 3 who were rated 400 points above me however.

This tournament:

http://www.colorado-chess.com/newtourn.shtml#467

has two sections and I can enter the U-1500 if I so choose, but I feel I wish to be challenged and learn more than a chance at playing for the prize money in the U1500 section. I think I will play in the Open section instead. Opinions?