I just like Atom better. One single namespace (plus GeoRSS makes two), and distinction between full and partial content won me over. Hopefully I can pull this off without flooding Planet Geospatial. All my timestamps are OK, so if anything goes wrong I blame James and Mark Pilgrim's FeedParser. I've switched Pleiades over to Atom as well (example: bridges), and contributed a patch to OpenLayers that enables mapping of Atom feeds.
Update: I did everything right and still flooded PlanetGS. Makes me much more forgiving of the folks upgrading their Blogger accounts.
Update: I added the missing rel="self" and rel="alternate" attributes to feed and entry links.