big anti-base weapons are a good idea, but only if you come up with a good and fair idea to prevent people from blowing up bases for petty reasons or ooc grudges or just cause they can.
distributing them only to like official factions is also not the optimal option, cause not all official factions are automaticly responsible
so a model or a concept is sound if the gameplay and fairplay concept fits the bill, too
edit: also yes, the lib SC is basicly what it ought to be. in a way - there could be 2 variants of the same model - one that is an actual SC the other i an anti cap sniper - but the model itself is the vanilla concept of a base destroyer