The same caliber for both of us certainly makes alot of sense, and would likely be adequate in most/all possible hunting scenarios. Things that come to mind that give me an itch for something that hits a little harder would be:
-oryx
-moose
-bull elk at longer ranges (approaching 500 yards) (More specifically looking at burning preference point hunts in CO in the next few years).
Again, I think the 6.5 CM could do all of these, but something bigger would give me more confidence in those scenarios/eliminate the variable of being under-gunned (maybe an irrational concern). Maybe I am putting too much weight on the suppressor idea, but the idea of me having a "bigger gun", suppressed, would give the wife the ability to comfortably jump up to something bigger (my gun) if/when needed on one of these more "once in a lifetime"/preference point elk hunts (where she would specifically be targeting a bigger bodied animal).