Are there different paces you can join?
Yes. Note that you'll need to be in the same corral as your desired pace, or you'll be waiting for them or rushing to catch up.
I didn't realize that there had been the change in pace groups, and for me it's too much mental pressure, so I have never joined them. But I encountered the 3 hour group at Star Wars and was around them for at least a mile. They were a big group, and they made it very difficult to maneuver around.
I'm a run/walk person myself, so I have no issues with how they are doing the run, but I was trying my darnedest to follow good etiquette (sometimes it's not possible based on the people around you and what has been going on, or your exhaustion level), and poor etiquette just bugs me on the course. It was the last few miles, so we were all tired, but they were just a big clump.
And now that I know it was a Galloway group, I think that people should probably write to him about their issues with the groups. I chatted with them both before and after the 10K (had to go back to the expo at around 2pm Saturday of Star Wars) and we were chatting about some of the things I experienced during the 10K. I was in E corral and I wanted to invite him to run in a further back corral so he could see what it's like. He said that he has run further back before, but seemed shocked because "people in those corrals are most of the people we work with" (that's a paraphrase, not a quote).
So I bet he would be very interested in knowing how others (especially other run/walkers) are perceiving and experiencing those groups.