If you already own one I would say it add something else to it, but to buy a MP40 for a fish only setup seems to be over kill. The random flow is mainly for SPS coral, where you need super high & random flow for growth stimulation & feeding. For fish only you can setup any kind of wave maker or alternating power heads to give the surge effect that fish like to play in, and it will help with dead spots.
Again, I am not sure if you already own a MP10, and looking to add to it. Or just looking at buying a MP10, but you could save yourself a lot of money at just looking at some of the New Hydor Koralia powerheads, hooked up to any kind of basic wave maker. Then spend your extra money to upgrade your skimmer, or extra LR. That will really add benefit to your system.