So far, I have found the filters to be a good fit. Based upon a thread in which one was cut open they do have a novel design that includes the bypass filter disc. I have about 15,000 miles on the oil so far and it has not changed its shade of brown since about 5,000 miles. My original fill was with Mobil 1 AFE 0W-20 and my make-up oil has been Mazda's 0W-20 w/moly. I happen to have a few quarts left from my full case purchase in 2012.
I'm keeping my eye out for any signs of varnish. The valve train area, so far, remains bright, shiny, and spotless. As stated above, the Skyactiv engine runs pretty cool and its design is specifically intended to lower internal friction.