I notice that the OB makes a slap slap noise even in calm water. Is there a fix for this?
You can also hear the water rippling past in sync with the pedaling strokes on the Mirage Classic. I think it's a byproduct of the old hull style. I suspect you might diminish it with weights but doubt that it can be eliminated.
Most people wouldn't notice it -- until stepping into the Adventure which, by comparison, is downright stealthy in smooth water. It's really great for sneaking up on people -- and wildlife! You've probably also noticed some other differences: against swells, turn radius, dryness, paddling comfort, etc. Between the two, you should have all the bases covered. For example, when fishing, your wife will be better able to bait the hooks with those wide trays while you can assist by holding the rods.... You can see that hers is the more important kayak.