Real life experience from this thread http://forum.mikrotik.com/t/ddos-story-or-warning-use-conection-limit-with-caution/49743/1
Anyway, use cloud core routers for production environments and you don’t have to worry for compatibility issues on x86 machines. Plus, router have more ports.
Are your routers going to face the public internet to make you worry about DDoS attacks?