is there any point in messing with trying to get a realtime kernel
working, or just use the default?
Just use the stock kernel and do your stuff. Once you have an optimal Jack configuration, and you know how your workflow is, try a realtime kernel and see if it helps. Any significant difference will be immediately noticeable. If it's not significant enough, you won't notice anything, and therefore can skip it altogether, i.e no point.
For some workloads and hardware, the RT kernel makes all the difference.