However, I have problems assessing the situation: gunboats should be 500 ton craft (ship cutter) and the meteorum is both a 1000 craft and described as a corvette (although it lacks FTL). Also, the power rating of the meteorum is superior to the gunboat class in general.
Perhaps as a testbed in kessrith territory the meteorum was deployed in a gunboat role (parhaps before the devellopment of the adscriptius) and also perhaps the kessrith were more able to defend against hit and run raiders given the heavy firepower in their ships (that's why it would have been used as an ambusher in "graveyards"). However, even with 100 tons added for the FTL drive, it could still be carried aboard leviathans and use it's firepower in hit and run tactics. The meteorum is too strong to be a gunboat anyway: it could cripple a cingulum and even damage an escort as it is.
I say add FTL to the CWfront version of the meteorum and leave the gunboat roles to the adscriptius and M variant. Anyway, that's how I (for what that means) feel it

On the other hand, your comments regarding escorts seem right: perhaps it would be exaggerated to carry some on leviathans (or else, perhaps in the last stages of my story where new techs are brought to bear, but we'll have time to discuss this later). Anyhow, you are right regarding this: I would see leviathans (big ones like the illustris or other heavy units) capable of carrying gunboats (cutters) up to all corvettes (small, assault (TOG), fighter carrier AND tank carrier (varrying configurations according to what the situation need be and according to bay space: Don't expect to find a pharetra in a fulgur).
Also, what about a TOG tank carrier corvette called the harpy?
At last regarding tank corvettes: you are right: planetary invasions will mostly call for specific ships (like war transports: think of them as big FS triton freighters carrying infantry and tanks in a big pressurised container, freighters and cargo ships).
However, they would give the opportunity to leviathans to push a bit on the balance should they choose and when needed.
To lars: Hmm, why not? But I'll stick to those mods (they are more than enough work already). And also, strategy is very good and I encourage it, but I WANT to blast my shiva or overlord to sithmereens.

I truly hope you can understand the feelings or a relentless space sim fan.

Oh, and another thing: shouldn't we "add" a safeguard system to the pharetra to give it a fighting chance while no one's watching?