nah... i'd go for it if the C63 amg was an upgrade to the m3... i see both these two cars as equal... if you are upgrading to a 911 or something then it might be a different story.
Current: 2013 F10 M5 & 2013 GLK350
997.1 GT3RS (gone)
2009 WRX STI (gone)
e92 M3 (gone)