The only issue I've come across with this sync service so far is that episode playback position doesn't reliably transfer between my iPhone and iPad. I'd like to say that I can pause an episode on one device and pick it back up on the other, but that hasn't been my experience so far. The second device acts as if the episode hasn't been played at all.
That seems like a big issue to me. I use Instacast on my iPhone, iPad, and Mac, and I rarely have any issues with sync.2 I cannot imagine moving to a podcasting ecosystem that: (1) has no Mac app, and (2) does not have reliable syncing. That sounds terrible.