So all your acquaintances buy a special new bike so you don't have to deal with yo-yo-ing....
Wake up!
Meanwhile, the jury is still out on the issue of FG in group rides - personally, as long as one has a front brake and doesn't ever have to rely on skidding, I don't see a problem with them. Your concept might alleviate the yo-yo issue, but I wonder if it would address the failure to maintain a straight line, too (my pet peeve in group rides). It would only work on flat terrain like you say.