Patrick,
I have a Europa, and a Dragon's Wing with Signature electronics. I think the what the Europa brings to the party is the ability to boost freqencies when you want them. Sure, the Q switch is a boost of sorts, but the treble and bass boosts offer something that the filter and Q set up just can't. Doesn't make the Signature set up bad, just different.
I don't think you'll want to sell your MK. The Europa will augment, but not replace that instrument. Like any bass, there will be times you'll reach for the Europa depending on what you're doing. At other times, the MK will be in your hands. They're both Alembics, so I think it is a win-win situation for you.
I own five Alembics (Essence X 2, the Europa, my Dragon's Wing, and a Spyder). I love them all for different reasons, and I use them for different things sometimes. I surmise you'll approach your Europa the same way. In any case, it's still an Alembic. As I see it, you can't lose.
Enjoy,
Alan