I have a 4PLS now, is it worth upgrading to the 4PV? or are they basically the same radio with different ergonomics?

The main difference is that the 4pv uses a newer protocol which may or may not make a noticeable difference in latency. But I don't know what the latency difference is for the Futaba systems.

Personally if you're happy with the 4pls then there isn't any huge reason to upgrade yet unless you want something new. I'm still using an old Sanwa MX-3x and I'm gonna keep it till it fades away