I find the "endgame" weapons in Sins very underwhelming. I don't know about you guys but .... I find them to be one of those "Oh, I'll build them for teh lulz" more than "I'll build them because I need them"
I might be doing it wrong but IMO the endgame tech needs something better than what's on offer currently. To be perfectly honest, the Nova cannon and it's cohorts should have just been Titans in the first place, since Titans are wayyyyyy more interesting than a static gun emplacement you can fire every couple of minutes and wait for it to connect with a planet insta-neutraling it.
They are a minor inconvenience more than anything else to me.