Madjak30--
Well WHEN we were together we rode in formation...But they were on MUCH faster bikes than me....so all it took was them to open it up and I was riding solo...lol But I could see them from afar and I could see they maintained positioning...
Basically it was understood that they could do their thing, and I would ride my own ride too..And we had agreed upon meeting points if we lost sight..... (at one point I was literally riding solo through the rockies, being that it was my first time riding in the mountains AND through torrential downpours, I was going between 80-90)
That being said, when we were in formation I was riding sweep, and I was not riding as tight as they all were... Still being new to the formation riding and all. Plus my first time riding with them...
So basically, I think the key is what we were taught... "RIDE OUR OWN RIDE". Discuss beforehand what the plan is, and have set meeting spots... I would be a little frustrated too if the person I was riding with was fluctuating such extremes as well. I am like you, I tend to ride about ten over...maybe 15, but usually flow with that one speed...
However the other time I went in a group ride with 3 people, we were all noobs and we maintained position our whole trip, and it was a nice and comfortable time...We discussed speeds and made sure everyone was okay with it, at the stretch stops...
Anyway, not sure if that sheds any input?