When I took the picture I wasn't done cable managing, hadn't yet secured the PSU, front panel cabling still dangling. Some of the defects you mention in cable management still exist, though, so thanks for the input! This is my first case that offers proper cable managment options, obviously I'm having a hard time utilizing those properly.
I really hope I'll not be too lazy to try out your fan layout solution. It looks very interesting. I feel like the current solution should do better in terms of pure GPU stress testing, while yours should do better for all other cases, i.e. pure CPU stress test, and CPU+GPU stress test. Where the CPU+GPU case is the most important one, unless the GPU comes with really poor cooling (I am seriously considering getting that horrible piece of trash thing from "Silence your Gaming PC with THIS" video, because GPU coolers are just so bad).