IMVHO gel fuel based engine does not give distinct advantage for military ballistic rocket engine, in fact hybrid engine (that is where gel fuel is used) has many pain points. The only distinct advantage hybrid engine offer is abelity to abort. Their ISP is only shade better than solid stage and significantly poorer than liquid engines.
Space tourism craft has found hybrid engine useful, due to safety as well simplicity to change thrust as well to relight the engine as part of trjectory.
Space tourism craft has found hybrid engine useful, due to safety as well simplicity to change thrust as well to relight the engine as part of trjectory.