I haven’t tried any Piefeds or mbins. My impression is similar to yours: interpreted language and “no fancy design patterns” gives me the idea it’s probably great for quickly prototyping new features like categories and moderation tools, possibly at the cost of performance. If you’re looking at hosting, maybe reach out to a few piefed admins, ask what they think about it and if/when they tried Lemmy for a comparison.

The great thing about the Fediverse is afaik you can test other instances and even other softwares while still getting access to the same communities and posts.