Great to hear that you're enjoying your new Maverick Pro II!
Between the Pro II and the Elite II the biggest upgrade is going to be the higher grade of neoprene. This does slightly change the sizing chart and the more flexible suit does make the sizing more forgiving.
The other big upgrade to the Pro II is going to be a more buoyant aerodome centerline buoyancy panel and the addition of our RS2 panels on the outside of the legs. These panels work together to enhance your body rotation while you're swimming. The centerline panel helps your shoulders roll and the RS2 panels takes away the restriction from driving your hip down into the water.
The other thing to bear in mind is that the Pro has fabric forearm panels, which are supposed to help with feeling the water, but also have the effect of insulating an area with lots of vascularization less well. That may either be a good or bad thing depending on the water temps in which you swim.
The Pro's RS2 panels on the legs also cause the suit to seal just a tad less well, for me and a number of others, and to be a tad less insulated there, too.
I agonized about Pro vs. Elite, and got in a bunch of swims in both before finally deciding that on balance the slight additional flexibility of the Pro was outweighed by the downsides of those extra "features." I've been very happy with my Elite.