6 to 7 Migration Tips?

I’ve just tried to migrate my RB4011 from 6.49.2 to 7.1.1 most of the config upgraded fine with the exception of my routing table had routing marks for PCC and also all the OSPF and BGP config got dropped so I would have needed to invest more time in rebuilding this config in 7 so I ended up just net installing back to 6.

is this anything I can put in place before re-doing the upgrade which would help retain any of this config?

The largest difference configuration-wise between v6 and v7 is exactly in parts you mentioned. We can hope that MT enhances the config auto-converter but until they do, it’s best to “reinvent the wheel” and do those parts from scratch in the new way. Often that’s a lenghty process and is not doable in due time in production environment, one should learn the new way in a lab environment.