@Martijn if you are happy with the settings on your 6800 use the same on your new appliances. With R81.20 you should enable dynamic balancing (default configuration => enabled), but "PRHF-37532" a known bug we felt in as a result of the specific network traffic of thei Maestro environment.
"Each time the core split is modified by the dynamic split, it invokes mq_mng -o to update a temporary file. A bug in this process can result in potential high CPU usage on the SGM, leading to traffic interruptions."
A private hotfix is available to solve this problem. We moved from 16600 appliances to 9700 and set 4 cores as SNDs and we are not using dynamic_balancing. We did not used the private hotfix because we don't like private hotfixes in Maestro environments (to much problems with updates).
We have other environments with dynamic_balancing enabling which are working fine, but they have to handle different network traffic.