I don't like riding in groups. I am faster than most when I want to be and those who are much faster tend to have a total disregard for the law. I pick and choose who I ride with most of the time and apart from safe overtakes I tend to be pretty much on the speed limit with making progress, as my priority.
My g/f is now pretty quick but we often ride with a newbie lassie. We tend to put her at the front so we ride at her pace which at times can be dangerously slow.
It's all about being in the right gear, position and reading the road. Why make an overtake if you have to brake hard or cause someone you have just overtaken to brake. Keep it smooth.
Advanced training of some form will greatly help whether you stick it out for a test or not. Often if you join an advanced group, you will find you are riding with a large group.
I'd rather take my time than not arrive at all, and I don't like riding with people who push the whole group.
We did a ride for heroes last year. None of us knew where we were going and the lead rider was not allowing for new riders, guys with slower older bikes (Old Brit bikes) and traffic lights in town. It was not a good ride at all with folk getting lost or fed up and heading home.
I orgainsed a ride out locally and did the scenic route as a group as we wern't going over 35mph, then split the group into fast and slow for the more open roads. I picked roads that were interesting and fairly long so people couild go at their own pace and at the end, everyone would get back together.
It workd a treat though obviously you wont be able to that on every ride out.