I have both, just not the supreme models. I've got the standard Core, and the Legend LX. I don't dive cold water so the supreme doesn't buy me anything. That being said, they both breath about the same. As Nemrod said the only real difference is the adjustment knob. The Legend LX knob adjusts the venturi as well as the cracking effort. The Core just adjusts the venturi.
If I had to buy again I would actually just get another Core. Yes the LX looks more substantial, but they both breath the same. The Legend first stage is comically huge compared to the Core and the 2nd stage is pretty much just bigger to look bigger.
That's just my opinion. Either regulator works fine, and you won't notice a difference in how they breath. Obviously looks do count (lets be honest here), so that's a matter of personal preference.
Make sure you thank your wife, maybe you can get a new BC next year!