Well I haven't tested a lot of them so not sure if it's relevant but I use DoggCatcher as a player and another app called Presto that shims the Android audio layer to increase the speech rate transparently for the player app. It's Presto that uses the Sonic library.
Do you have a link for Presto? I can't find anything about it online.
Hmm, now you got me worried. I use a dedicated device for podcasts that is still running Android 2.x. Prestissimo seems to be the new name, but itself deprecated in Android 6.0. I'll have to look into that before that device dies.
What application do you use for listening?