I think in order for the Oberth and other Tier 1 ships to be viable additions, there has to be some kind of mission for them. Currently once a player reaches a certain tier, the lower tier ships become useless even if you put X level weapons on them.
I know there are calls for some zones, missions, or PVP maps for runabouts. I think a similar mechanic must be added so that lower Tier ships can be useful even if the player is already an Admiral.
I personally wouldn't mind the smaller Maquis ships to be added somehow, even if it has the same mechanic as a runabout. I think Chakotay's Maquis ship in particular is large enough that it can be the Tier 1 Escort you are looking for. Plus even in that DS9 season 4 mirror universe episode, you can see that a Maquis like ship piloted by Bashir was nearly the same size as the Defiant.