My wife and I have only been riding for 5 years, but we have ridden 45,000 km each of the last 2 years (each on our own bikes) and have therefore come up behind a lot of groups. On a 4 lane divided highway they aren't a problem, but most groups head for the quieter 2 lane roads and it has been our observation that for the most part they are more of a hazard than anything else - if they are of this "manageable size" of 5 to 7 bikes. They are often going the speed limit, which is fine, but they often have at least several vehicles behind them that are reluctant to pass. We don't mind mind blasting around them (my wife rides an FJR), but not everyone has either the power or the inclination to ride/drive like that. Maybe even smaller groups together would be more appropriate.