Sorry to hear about your pump problems. I've been monitoring the various DC pumps because I like the idea of using them, but I'm curious how reliable they are long term. At MACNA this year, I spoke with the Royal Exclusiv folks about their DC pump now available in the US. It's not cheep, but they seem to make a good product.
This is just my approach, but I like to put twin return pumps on my system that are rated lower so that even if one goes down, you have at least half of the flow still maintained. This means extra plumbing, space, and money, but redundancy gives you some peace of mind especially if you have a third matching pump on hand to swap out. Again, that's more money, but we do invest a lot of money in coral and fish.