If you're worried about the Evo coping whole mountain - I rode it in the Alps and it handled
everything just fine, steep blacks, charging, off-piste, sheet ice, moguls etc. The only thing that really
gave it trouble was frozen rutted off piste conditions (like a frozen ploughed field) but I don't really blame the board there (at my level anyway) it was unridable.
However charging in slushy conditions particularly did push the board around a fair bit and I had to put in a lot of work and pick lines around things rather than through it.
When I tried the Proto, I immediately appreciated the extra stiffness in the board over anything lumpy though. It was still ok to butter and press.
Getting back on the Evo afterwards was super fun though - it is a playful board
The Proto 154 sounds like a good match for you. Either will do the riding you want just, with the sweetspot being a little nearer to each end of the scale.
Anyway FWIW I'm on an SL 155 for this season as I really only dabble in the park.