is it okay to use a high quality filter ie wix or amsoil.
short answer - yes.
long answer, Subaru filters (in addition to being of high quality generally) are equipped with a bypass valve set at 23psi. This value is higher than 'most' aftermarket filters (I recently read there is a Wix filter that is set at the Subaru bypass value.) Most owners doing reasonable maintenance are unlikely to ever detect a difference in engine performance or lifespan. However, Subaru filters are not expensive, particularly if purchased in sets of 3 or 6 from an online dealer such as subarugenuineparts and others. Your local dealer may even match prices.
others will likely chime in with their own opinions.
google oil and oil filter questions and read all day long. no need for *another* thread. everyone likes to talk about oil and oil filters, i suppose because it's the one question where everyone is right - because it doesn't matter.
this question is more about personality than anything else. that you're asking and researching suggests you are strongly focused on oil so to that end you'll probably be the personality type that wants to use OEM. if you're worried about it, go OEM, there's certainly nothing wrong with that. but truth is these engines routinely see 200,000 miles and choice of oil or oil filter has nothing to do with it.