As UhClem mentioned, QJets use ammonium perchlorate based propellant which isn’t compatible with staging via ignition from a booster motor burn through - APCP sustainer motors are (now) typically ignited electronically with a flight computer of some kind and an ematch/initiator or something similar. Years ago folks used variations of cannon fuse light by the booster motor ejection charge but electronic staging/air starting is the accepted practice now.
electron for rockets is getting better and better and smaller and smaller, still a bit beyond practical for low power staging purposes to my knowledge.
Black powder staging is certainly low tech but carries its own challenges, particularly with long gap staging.
The first challenging is getting the booster ”blow through” flame to ignite the sustainer. Interestingly, with proper ducting and venting, THIS isn’t nearly as hard as it looks. I’ve done over 50” reliably.
the second and often unrecognized challenge is that the BOOSTERS on long gap staged rockets are often stable after separation, and even if they are not stable they are by definition somewhat larger and don’t tend to recovery well by tumble recovery. So you need some sort of system to deploy a recovery device on the booster. Electronics is not technically “out”, but at Least to me seems kind of silly to use low tech black powder for booster ignition and electronics for booster recovery deployment.
in any case, a C5-0 would greatly expand the Practicality of staging rockets with 18 mm motor mounts. It will probably stage LOWER than with a C6, but since most people are staging for kicks rather than altitude, the lower the staging the cooler the flight is to watch,
the exception would be my Apogee II, with I think a B6-0. My Dad and I watched the flight and saw the sustainer come down, never observed the staging even. Of course, after a short search the booster was found where we never expected to find it and therefore didn’t look for it…..it was still on the pad.
apparently it staged so fast our eyes just watched the sustainer go up while the booster slide back down the rod onto the blast plate!