I've been using NetNewsWire for some time now. I am still running version 2.1 on my MacBook Pro—I just never saw any point in upgrading. (There didn't seem to me to be anything important that 2.1 couldn't do. And one time I did download version 3, and found the user interface changes confusing.)
This afternoon, I downloaded (the now completely free) NetNewsWire 3.1.3 for the Mac Pro. I figured I would tough it through the UI changes and see how it goes. The only reason I did it at all is because NetNewsWire claims to be able to sync your subscription lists between different instances using .Mac. So I enabled syncing on the MacBook Pro, told it to merge its list with the server's (which is presumably blank to start with), and then synchronised. Then I enabled syncing on the Mac Pro, told it to download a copy of the server's list (planning to change it to merge after this first sync), and then synchronised. Almost nothing at all happened. The only discernible change was this: the article list for Daring Fireball (to which I am subscribed on the MacBook Pro, and which I presume is one of the default feeds for a new install of NetNewsWire) seemed to update itself to mirror its status on the MacBook Pro. Nothing else happened. In particular, it didn't subscribe me to the feeds I had synced to .Mac from the MacBook Pro.
Next I tried exporting my subscription list from the MacBook Pro, and importing it on the Mac Pro. Firstly, it dumped these in a top-level folder called "Imported Subscriptions"—an option to overwrite the existing (and in my case completely unwanted) list would seem more sensible here. And secondly, none of these were updated to mirror the read/unread status on the MacBook Pro.
I had one last idea while I was typing this post. I just manually deleted the default feeds to which I'm not subscribed, put the three to which I was into their proper place in my hierarchy, then moved the whole lot out of "Imported Subscriptions" up to the top level and deleted that folder. Then I synced again. Nothing. Top to bottom, apart from Daring Fireball as mentioned above, every feed is being displayed as completely unread.
Anyone care to suggest what I'm doing wrong?