I've only eaten mutton in heavily spiced dishes and it does go very well in those settings - you need other strong flavors to stand up to the gaminess of the mutton, which might be why it hasn't caught on in American cuisine which tends to focus less on heavy spice profiles and more on just cooking ingredients to present their natural flavors.
Yeah - sounds a lot like the various dishes across a range from the Mediterranean to the "-stans" that I've made with lamb. No reason I couldn't use mutton - if it were available. I've had some lamb that was absolutely overpowering, so having a hard time imaging something more than that.
I've never eaten mutton, but I'm wondering if its stronger flavor would be fine in that stew.