I just upgraded the SGreen so it's not worse than the Fusion Morter anymore... lowered its recharge to 30, effectively increasing its net DPS by 50%. I've been making a bunch of little tweaks to my tables for the sake of balance. I understand that GTVA weapons should be worse than Shivan, but the SGreen is outdamaged by the ULTRA-AAA, for crying out loud. Also, I've always thought that the Mentu is the Vasudan Aeolus. One SVas (which, with my configuration, is anything the cruiser will probably ever bring to bear at once on anything short of a destroyer) is about as deadly as two of my revised SGreens, which is what the Aeolus can focus. Granted, this is starting to get a bit out of hand insofar as the original scope of this conversation, but still, it's an idea.
EDIT: Just wished to add that I've been testing, and the Mentu is pretty evenly matched with the Aeolus with this setup. It's kinda random which dies first, and the other usually has less than 15% hull integrity left. Both are pretty much hosed by a Rakshasa, though.