Dh and I did chilly hilly 2 years ago and really enjoyed it. It was challenging enough that it felt like we'd really accomplished something when it was over, but we weren't dragging or anything like that. There was a camper on the road creating a huge bottleneck when we encountered the steepest hill, so it wasn't physically possible to stay on the bike without riding left of center. People were dismounting in droves and others were riding on the wrong side of the road creating a very dangerous situation. There are riders of all fitness levels which seems to open up many possibilities for collisions. Not sayin' where I am on that spectrum, but I recall hearing one of the "bandit" riders complaining about being stuck behind me: "How do you go that slow and not fall over?" he said to his buddy who advised him just to suck it up and wait until it was safe to pass. Many more don't/won't wait.