I am a fairly new user of Patch Manager, but I recently learned that its impossible currently to synchronize or auto-publish only the most recent updates in a catalog, rather than synchronizing or publishing the entire catalog.
For instance the Mozilla Firefox catalog has almost 8 years of updates, or about 400 updates, which would need to be replicated across multiple database instances before reaching our clients just to publish the updates from last week automatically.
I think if Patch Manager was able to filter out older updates when synchronizing, for instance only sync updates from the last 6 months, or even better only to synchronize the last few version numbers of each product. Then auto-publishing an entire catalog wouldn't be an issue, as the catalog would only have a few updates per product.
Note: although I don't think it really impacts the issue mentioned above, I am using Patch Manager to support an SCCM instance, rather than in its natural WSUS state.