Envy.
This is exactly what I do. My throwing putters are:
Ti Zone > kinda beat JB Zone > Neutron Soft Envy > kinda beat Electron Envy
I've never had the tacoing problem with Jawbreaker that some others have had though, and it is an awfully large stability gap going from a premium Zone to an Envy. But for someone that only wants to bag 2 throwing putters, a Zone/Envy combo with both in durable plastics is a fantastic and very natural combo. Personally I find myself throwing the JB Zone the most on approaches, and the Neutron Soft Envy the most off the tee.