I upgraded to an AC110 after my 1 month old cfs500 suffered a catastrophic failure and pumped a lot of water out of my tank. As to why it broke. I may have let it get to full of crap and I may have tightened the lid to tight, but neither of those things should cause a major failure in a quality filter.
If you want a canister filter spend the money and get quality product not an Ebay knockoff.