Shooting one handed makes one pay more attention to the basics... sight alignment and trigger control.
I shoot Bullseye at the Sharpshooter level. On a good day, I can plunk bullets one handed into a pretty small area.
I also carry a gun for a living. If I have to defend my self and or others, I will use all the hands at my disposal.
Practise both. Incorporate that sight alignment and trigger control into the fast two handed style of shooting - don't abandon it.