Yes. I have indeed tried leaving JFR on in production. For many years. We even used to take chunks from the repo continuously (even though not supported). We solved 95% of our production problems with only the JFR data (with some contextual data recorded), rarely having to ask for other pieces of data or run special builds with additional one-off instrumentation. JFR is not only a production time profiler; but it is pretty awesome at that too...