First, I would like to thank Daidalus Team for their efforts and continuous work on IL-2
I have one suggestion for future versions: Change the skins file format from BMP to PNG. A quick test on a fresh 4.09 install shows that I have about 2 GB of data in the PaintSchemes folder. I then ran a batch conversion of all BMP files to PNG, and the result is about 480 MB.
I guess the choice of BMP was natural as a lossless format when IL-2 was first released, since few tools supported PNG back then. But now PNG is widely supported, and provides a lossless format and a nice size reduction.