I would look at the known issues of 8.1.8 before installing, as there is currently an issue with the AUX ports not coming online in the 5200 series that may render it a non-starter for some environments. I'm still in the process of validating 8.1.9 for a wide-scale deployment (actually going on the first production firewall set as we speak) but I would lean more towards targeting that release as your target if planning an upgrade in the comming weeks.
As for 9.0, I still wouldn't run it in a production Network unless you absolutely need the features added within 9.0, otherwise stick with 8.1 for the time being.
Click Accept as Solution to acknowledge that the answer to your question has been provided.
The button appears next to the replies on topics you’ve started. The member who gave the solution and all future visitors to this topic will appreciate it!
These simple actions take just seconds of your time, but go a long way in showing appreciation for community members and the Live Community as a whole!
The Live Community thanks you for your participation!