I still have two Penguin 350's in use. One came with a used tank purchased in mid 2017, the other I bought new same year. Both work well. Since the beginning, I modified the media in, so that it is washable and non-disposable (see attached image). I have never bought cartridges and don't plan on doing so.
Currently I have 7 AC 110 (=500) in use, and a bunch of smaller ones (AC 50 = 200), and one AC 70 (=300).
I like both of these filters (AC and Penguin), more than any other HOB filters, and use them for different purposes. They deliver their flow in different manners, the Penguin does so on a mostly flat-along-the-surface manner, the Aquaclear throws the water deeper into the water column. Of course one can modify the manner either delivers its flow.