Mikrotik Cloud Core Router and BGP real life experiences?

Depends. This router isn't running BCP-38 as it's run at our borders.

Looking at the specs. Firewall rules do take it out of fastpath. Which
means it's going to take a decent performance hit on paper. I'm not sure if
their auto method of enabling BCP-38 IE. the IP>Settings>RP Filter method
would accomplish the same outcome, Without taking the router out of
fastpath. I assume it works the same as using firewall rules. Just "Behind
the scenes".

That being said, Real world testing. Running the traffic levels I mentioned
before. I put a single simple firewall rule on the router. Which
effectively took it out of fastpath. And also enabled connection tracking.
I saw no noticeable change in CPU load.

Nick Olsen
Network Operations
(855) FLSPEED x106