Have you tried zita-rev1? There's a good reason right there to keep Jack around
I use Jack for a lot of live stuff, say, running a synth through zita-rev1. If I wanted to capture that I could either run a realtime render via Jack (Cadence) or route the audio back into Reaper or similar. Either way, there are plenty of occasions when Jack is necessary for my workflow.
On the kernel front, I love the Liquorix low-latency kernel. Zero x-runs since switching to that (ensuring that "performance mode" is selected in Cadence).