In all the time since its debut I've only seen a Marauder Cruiser ONCE.
Must have been me..I some times feel I'm the only one piloting that ship, but to be honest its the only one I've bought that i have enjoyed.
A reason your probably not seeing many of these flying around is lack of fleet versions, and that (In the gorn ships case) there are many better options, so really the only people flying these are 'theme' characters (Like my Orion with her all orion crew).
On the other hand, the factional fleet ships (Naus for example) seem to be all over the place.
Now will it sell? yes it will, why? because its an escort.
... The Nebula is supposed to be a science ship/cruiser hybrid and it did wonderful pre-f2p when sci abilities were worth using. Now however, this ship can't do science so it must focus on being a 'science-y light cruiser' ... and it fails because its hull is so weak the bleedthrough damage makes it super easy to pop. It is not fast, it does not turn.. the only thing this ship can do nowadays is shield tank and put out mediocre damage.
It should be updated in the fleet version at least to be Cmdr Sci, Lt Cmdr Engineer, Lt Cmdr Science, Lt Tactical. Only then does this ship have a snowball's chance in hell of becoming remotely useful.
I have a sci-Nebula Retrofit. I think its an excellent light sci platform. Its turn rate is not bad and its universal slot means its flexible. Nice little crowd controller.
As for the Andorian ship I've heard its coming end of February and I think its an awesome looking ship, big guns and rumoured sideways tac slots. Interesting to see how that works.