I looked into the idea of hybrid for a while but soon dismissed it.
I think your trying to add redundancy to solve one problem but by doing so increasing risk of bigger problem.
Hypoxia isnt a risk on a ccr at any place (other than the surface or shallows) so worst case even if your o2 feed system fails the most thats going to happen is your going to maybe effect your deco. The degree of effect will depend how frequently your checking your handsets or if your running near min loop. Either way your parachute isnt needed to stop you going hypoxic during the dive - thats almost impossible to do (other than in shallows when you will be running high ppo2s anyway for deco and not being distracted so much from checking.
Hyperoxia is a big risk (far easier to get than hypoxia) on ccr especiallly deep. PPO2 can increase rapidly at depth with little/no noticeable change in loop vol. Your degree again of risk depending on time between checking handsets.
Adding a 2nd O2 injection method effectively doubles your risk of a failure leading to hyperoxic loop. Stuck open solenoid, leaking,bypassing orifice manual inject oring bypass.
So yes solenoid parachute will reduce risk of hypoxia in shallows during ascents (but even then you really would have to work hard to do it and not be checking to go hypoxic) - but at the same time it does increase risk of loop going hyperoxic by leaking.
Afterall if your going to counter risk of hyperoxia (thru one of the o2 systems leaking) by relying on frequent monitoring - then you dont need the redundant o2 system in 1st place
as your monitoring!
after considering the above I decided it was little advantage, some disadvantage, some extra complexity - so not worth it
I also found seldom used solenoids (when running eccr manually) stick more freq and are less reliable than ones used all the time)- so that may make an unwanted o2 leak even more likely