You can just put the star base in the best position relative to the most likely direction of attack from incoming phase lanes... and then scootch the star base a little closer to the PLANET than you would think you probably should - and then it can defend the planet QUITE well. Especially when you support it with a good mix of tactical structures, and are ready to call in a fleet when needed.
Further more, you can deploy mines - intelligently - that will, as someone mentioned before "funnel" the enemy to your star base. And when that occurs? Try having a few mines right by your base, as well - they don't hurt friendly forces (although I think that they probably should, but that is neither here nor there, so to speak). Also... you can cover weakspots with tactical structures - they are really quite a lot better now.
Really the Vasari star base moving, isn't as much of an advantage as you think... it actually forces you to spread out your tactical defenses a bit more, because you can't make just one well fortified little point. That coupled with the fact that even the slowest ship in any fleet moves considerably faster than an Orkulus means that moving the damn thing can actually wind up hurting your position.
As for the Orkulus on assault? First, you have to get a builder there - which dies easily. Then, you have to deploy, and protect it during deployment - which is, almost impossible if the enemy has any decent number of bombers (omfg, fleet diversification? NO WAI!). Then, you have to upgrade it at least once, and most likely another couple of times to ensure that it's actually going to do well. And finally, you have to do the battle itself - in which time the grav well has probably be reinforced with an armada ready to rock and roll.
The TEC/Advent Star Bases have abilities that play to their strengths that more than balance grav well defense. Also, you REALLY need to look at the whole picture... The bases, and tactical structures, mines, ships, etc... all play together differently per faction. TEC/Advent Star Bases only don't own up to the Orkulus - if you play them as if they WERE an Orkulus!
L2Play people, thats what it really comes down to. You have to know your enemy, AND yourself to have any good measure of success (true story, ask the ancient dead chinese dude).
/thread
-Itharus