Yes sir, for sure. I am on two of them every day for they far surpass others (apart from Waterfox classic, and Basilisk) in functionality and only a few sites need a modern html5 rendering engine for now. But you can use others as needed, thank God.

There is a reason why Firefox redesigned their internals - better use of multicore processors, better security, a faster rendering engine, sandboxing. I want to go into the future not get stuck in the past.