I know this post is a few years old, and I wanted to comment on the firmware differences between the MX65 and MX68. The MX65's maximum runnable firmware version is up to MX 18.1xxx, as per this documentation that discusses product firmware version restrictions. It cannot be upgraded to MX 18.2+ firmware or any newer major release versions. If networks with these devices are set to run newer firmware versions (such as 18.2), they will automatically use an MX 18.1 firmware version instead. The MX68, however, can run the current stable firmware version MX 18.2+ and even the beta release version of MX 19.1.x. This enables features such as Firewall Logging, Trusted Traffic Exclusions (Advanced Security License required), Routed mode eBGP, and more! You can see the stable release firmware features for 18.2.X linked here and the beta release firmware features for MX 19.1.X. over here. Hope this helps!
... View more