I fooled around with a Filter flow that my buddy had in a house he was renting a few years back. It was from around the early to mid 80's. With much excitement, I brought my dog beds to his house and some laundry soap, along with some STPP. Unfortunately, I wasn't impressed at all with its filtering ability as it was a big let down. Maybe my dogs have finer than normal hair......or something, but there wasn't much hair in the filter by the time the wash cycle ended. Of course, I bypassed the lid switch and watched the entire time. LOTS of hair ended up in the dryer filter, though. It was quite a bit of a let down, but it made me more content that my Maytags did a better job with dog and cat hair from my animals than my friends filter flow.
I do remember peaking underneath the skirt of the washer sometime later trying to help diagnose a problem for him and it appears (going from a fuzzy memory here) that the pump drew water from the bottom of the tub for filtering. Well, hair usually floats to the top, so that could have been the problem right there. Maybe that's why they work better with lint since it's heavier than hair. My personal experiences.