There is a group that have these and they come out to the MUP I ride at and are most often there on the weekends. That's also when the local cycling clubs and bike shop riders are there. They absolutely hate these things because they cause them to slow down their pacelines since they are so hard to pass with them weaving across the path, especially when there are several of them. Personally, I don't mind them unless there are more than two. Then they have to ride offset to keep from running into one another and it really does make it hard to get around them, especially when you're on a bike path that has a bridge going over a major highway.