You've seen my setup Jonas, and I went with with preferred pinion angle. Yes, my springs have an arch to them, but they have been working just fine, even under full flex!
Every so often when I'm out wheeling, when driving along I can hear the springs 'clang' as they re-settle themselves into position.
Also, judging from your pictures, it looks like you may need to shorten up your LCAs by about a centimetre.