i own the MM 6501 components and love them, but they are power hungry and also operate ~3Ohm versus 4. i wouldn't buy them unless you're at least pushing them with the recommended RMS rating.
i have never owned the DB series, but many people like them simply for the bang-for-the-buck...
i owned the momo's in my last boat and they were great with 75-80W RMS per speaker-plenty clean and loud.
you could easily stick a pair of DBs in your garage for backups for less than it would cost to setup with the MM's.
my gut tells me the pricing on the MM's will come down significantly over the next year or so just like the momo's did before they were disco'd.
2003 X-2 MCX