I’ve had experience in both and find them easy for the end user, with the ability to check up on submitted tickets progress (by entering the ticket reference), plus (if we were to choose) there wouldn’t be another area to login to, just a simple form, where we can request basic information.
I agree with this but also @liam is probably right regarding the Discourse plugin, could we try creating a “Issues” category here to start with and if that becomes unmanagable then look at what other options there are (for example could the CiviCRM install @Graham be used for this?).
Civi can support a ticket/case management type workflow, but it would take a bit of time to set up, and I’m not convinced that this is best use of resource currently. So I’d suggest just using this forum for that and see where that gets us. At least then we’ll be able to gauge the volume and nature of the tickets, so that if we do need to build something we’ll have a grasp of the shape of it.