NewsRob 3.4 is coming out soon and I would like you to test it.
Among other things it adds a sync option: "Keep and Sync Unread Articles Only", which only fetches unread articles from Google Reader. It also deletes read articles on your phone during the next sync to make room for older unread articles in your Google Reader account.
A couple of people have already been testing it, but I would like to get some more test exposure for this feature.
So please have a look at this discussion, download the beta linked there and feed back into the discussion if it works for you or if something is broken.
There are also other new features in this release. You can find details in the discussion from above.