GSSP very well done. You must really like esoterica in cartridge development. I am envious but perfectly happy with the 6.5 x 55 that I have. If I go through some late late middle age crisis I might AI it and it would be close to your 6.5-8x57mm improved which is a good place to be. Near 6.5x284 ballistics with slightly maybe very slightly improved barrel life.

"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli