Reeder did a really great job of dealing with this. I use Reeder 4 and got a one time modal on launch that Reeder 5 exists and what the potential reasons to upgrade would be.
I use Feedly as the source and read with NetNewsWire on my iPad. There's a NetNewsWire client for the Mac that now supports Feedly but it doesn't support vi commands for quickly paging through articles. I don't use a keyboard on my iPad so it's fine that it's different than the Mac.