When I caught up with the gaggle just behind Jonny (who was now on his own). I flew right with Gerolf and behind Attila and Michi. You can find the IGC files here (Davis) and here (Gerolf). You can see in the IGC files how close we were.

Starting at 14:42:59 we glide together for 8:42. I glide 10.6 km at 38 mph for an L/D of 12.6:1. Gerolf glides 10.9 km at 39 mph for an L/D of 13.1:1.

Put the two IGC files in SeeYou and compare Gerolf's and my glide starting when we come together at 14:42:54. See if you can tell any difference. According to our instruments (GPS altitude) I started out 561 feet higher than him and ended up 580 feet over him at the end of 8:42. In actuality, we were almost at the same altitude (with me 100' or so over him), so once again I have very little faith in the validity of the absolute GPS altitude values (CIVL, you had better be aware if this).