My feedreader of choice is, and has been for some 2 years, the excellent NetNewsWire Lite on a Mac. It handles my 244 feeds very well, and they're all nicely categorised into groups.
But I've had a bit of trouble recently in that NetNewsWire Lite has begun to randomly jumble up individual posts. Rather than sorting them by arrival order, it's just mixing them together. I've checked "View > Sort By > Arrival Order" and it's checked. I've clicked everything and double-checked settings, and it should all be OK.
Just out of curiosity, I thought that I would try out NewsFireRSS. Its interface looks very clean, and I do actually have a license bought through the recent MacHeist promotion (I bought the MacHeist bundle primarily for Delicious Library and Rapidweaver). So I thought that I would give it a whirl.
NetNewsWire allows you to export your RSS subscriptions to an OPML file with two options: first, as a flat file, and second, preserving your subscription groups. I opted for the second option, as I've got them all nicely grouped, and it would takes ages to sort them again by hand.
Sadly, when I imported the OPML file into NewsFire, none of the groups were preserved. I had one huge list of subscriptions. Not good!
Just to test the exported OPML file, I imported it into the open source feed reader, Vienna. My groups were preserved, thankfully, so the OPML file did export correctly from NetNewsWire. It seems that NewsFire just can't cope with OPML groups - a big shame! I might have to relent and re-group by hand - or just stick with NNW or Vienna.