I also bought two MP40W's and a battery back-up back in March. They're great pumps when they're running correctly, but that's the problem, they never are. I had to buy a spare wet side just because it seems like I've always got one out for repair anymore. I regret ever buying them, and have chalked them up as the most costly mistake I've made on my tank set-up thus far.
They will be replaced with a pair of Tunze's soon.