In my post from two days ago I reported about gaps in my ground polygons, this lead me to discover the different resolution of BGLComp and BGLC generated BGL files. But it turned out that the gap was also caused by a programming mistake I made. The round earth correction was not completely correct for the P3D v2 output. I have fixed that now and as a result you can use the option to divide the polygons in a grid again. For the FS2002 style polygons that gave a better performance, I guess we need more testing to see if that is also the case for P3D. But in general it should be more efficient for the rendering engine if not all polygons have to be drawn.
The observations about the different positional resolution still stand, but they were not the cause of my gaps. So gaps fixed and still something interesting learned.