We are currently on 10.3 (Desktop & Server) and have been for 5+ years. Looking to upgrade to new version, cannot go to 10.6.1 due to third party software compatibility.
I have been told (by Esri) that upgrading Desktop up multiple versions is fine, but jumping ArcGIS Server (from 10.3 - 10.5.1) could cause issues. It was recommended to step up the Server upgrade (10.3 to 10.4 to 10.5).
We have the specs for all versions up 10.6 (SQL, RAM, etc.) I recently tried to upgrade on my desktop from 10.3 to 10.6 and it completely crushed my CPU (64 bit, i7 2.70 GHz 16GB RAM . Needed to get my computer reformatted, probably wasn't related to Esri and more than likely hardware/video card issues but it makes me hesitant to push 20 end users up to 10.6 and jump my ArcGIS Server to 10.6 and risk headaches and issues.
I am personally thinking moving up to the stable 10.5.1 and calling it good, including making the jump from 10.3 to 10.5.1 on server. I am aware of the changes that occur at 10.5x+ with ArcGIS Enterprise.
Any similar experiences, insight, or advice?