Have you found the answer to your question yet? At the very least you should be able to disable individual components of an AppInsight template to reduce overhead on your older SQL. I'm curious as to what version SQL you found not compatible with AppInsight.
Another method I have used with DBA's is to drop MSSQL sourced events into the Windows Application Log, and in turn use (1) component monitor to capture any error events detected in the Windows Application Log. By using special alerts rules I could notify specific groups to specific sourced error events detected.
Sorry for the delay.
You cannot disable parts of AppInsight, if you use it, you use all of it. All 50 licenses.
We have SQL 2005 and older...for now.