I just finished my first play session of the campaign, and, without any spoilers, its amazing. Playing through was just a wonderful experience. When I finished and went to check out the cool customization items I had unlocked(another super cool and rewarding experience), I realized something. All the armor customizations I had unlocked were only available for the mk7.
That means I have to chose between showing off and being rewarded for my campaign progress or using the armor pieces I earned. Having all those unlockables only work on the armor core that has paid armor pieces was such a let down and soured the sense of satisfaction I had gotten from hunting for those cosmetic items. We really, really need to have cross core customization, for colors at the very least if nothing else(but please having full cross core would be so, so much better).
Being restricted to an armor core where every customization item has to be purchased in order to use my campaign rewards is so scumy. It ruined what was otherwise a fantastic experience with the disappointment that is the greater progression system.