I am wondering that if they both complement each other as far a GC data is concerend. I already have JMX monitoring enabled but am looking into using GC detailed logs as well.
I will be using JMX monitoring in any case, so the question is if I should also enable GC logs as well.
You should enable GC logs as these will give you much more detail and record every event. (With JMX, you poll for changes so you could miss an event, if you poll often enough you can generate significant garbage)