And since the author's already here: A similar comparison between rspamd and dspam would be neat as well - I remember that I stumbled upon rspamd in the past, but went with dspam for some reason.

I think it was either related to learning (but rspamd can do that, right?) or the db backend (I didn't want to run multiple database backends and anything that didn't support postgresql was out right away). Then again, I might be completely off.