I'm not familiar with the Prius engine; is it a known sludger or have other lube-related problems? If so, I'd go with a premium filter. The EaO certainly is a quality piece, but at $15, is it worth it? Does the ROI pay out?
Could you get any other premium filter for less that would do a job as well, or nearly as well? For a 10K mile OCI, I'd think that you could locate a Wix, PureOne, Bosch DP, etc for "better" filtration, but less cost.
If I were greatly extending the OCI, then the EaO would be almost a necessity. But you're not doing so, right? Therefore the EaO is a bit of overkill, and probably will not give a decent ROI.
It's a matter of "good; better; best". Do you really need "best" performance for "normal" applications?
Maybe you can get "better" for less cost, and not worry about the "best"?
I did a cursory search on the Prius engine and tried to find any known lube issues, and came up with nothing. If there is an issue that I'm not aware of, then it would certainly alter my position here. As far as I can tell, although Toyota has had some known engine issues with other designs, the Prius isn't one of them. So, fear of terrible trauma is not warranted.
My point boiled down:
* Toyota filter for $5 will probably make the engine last a very long time, because of the good engine design with no known lube issues.
* A good mid-line filter such as Wix, PureOne, Bosch DP, etc would be "better" for around $8 or so?
* The Premium EaO, M1 and such are much more money, and do a fantastic job.
Keep in mind that the cost of products are relative to the OCI duration. We've seen it time and time again. Will you get less wear with a better filter? Yes - absolutely. Will it get down below a point where any shift in wear delta is tangible? Probably not.
This is almost exactly like the whole dino/syn oil debate. Where's the ROI? If you spend 3x more money on an EaO filter, do you get 3x less wear over that 10k mile OCI??? In 10k miles, are you going to see one-third of the Cu, Pb, Al and Fe wear metals from using an EaO? I seriously doubt it! To the contrary, in "normal" OCIs, filtration seems to matter little (if any at all) in regard to wear metal results. I would challenge anyone to show me conclusive proof that using a premium product for the OEM OCI makes any distinct statistical difference whatsoever. To be direct, I completely agree that the EaO will do a better job of reducing contamination in the lube stream, but to what end? Does it makes sense to invest 300% of your money for only perhaps a 5-10% wear delta, if it even exists at all, in the stated OCI?
If you're going to extend the OCI, then high end products make sense. If not, then "normal" products will do just fine.