There is absolutly NOTHING wrong with the blue filters. They are made to subaru spec's. Cardboard? SO what? Would you rather glue a paper element to steel or a similar material? Look at the inlet holes on the Suby filter. The number and size of them, no other filter I have seen can flow what that filter is capable of except maybe the Wix.
With that said, I have pulled almost every brand of filter apart. PureOne filters had a gaf relief valve, no filter had the correct pressure relief spring tension that Subaru calls for. Do you think Subaru would spec an inferior filter for their vehicles? I don't think so.
If you MUST get all crazy about not using a Subaru filter, do use the Purolator. Mobil 1 filters are a joke. Frams, well there just Frams.