Replacing current 30A with MPPT controller - make sense?

The differences between PWM and MPPT are not that great.
I agree with PT and would stick with what you have, unless you want to add that other panel.

Or perhaps you wanted a better solar controller? Perhaps with finer control of absorption V, timing and battery temperature compensation? Then yes, go for it. I have a Epsolar Tracer MPPT that works well. Very configurable. Can get an optional temperature probe. Not that expensive. They have a 40A version I believe.