Yeah, Podcast Addict is proprietary and ad driven, unless you pay. I grabbed a lifetime ad-free upgrade years ago when it was like two bucks.
On some level I agree with you, I generally love open source, and if AntennaPod had the feature I was looking for I would have switched, but I also don't mind paying for software if it's good and reasonably priced.
Zero info about whether it has a headphone jack or a MicroSD card slot, how long the software support will last, how repairable it is...