Yeah, this usually works well, in fact there are commercially available guitar pickup systems that do this. If DIYing, just make sure you have all the polarities the same (all the ground wires are connected to the outer part of the disc). Depending on what you’re mic’ing, there might be phasing issues, so I still like to run them individually into a mixer so I can mix to taste.
Are you wanting to put a contact mic on each bar? If so, it might dampen the sound, depending on how you attach it. If that matters for your purposes.