I dunno, I've been trying yalls' advice about forgoing most defensive structures... and it just doesn't seem to work; having a fleet is needed, don't get me wrong, but the ability to neutralize an enemy fleet w/ a defensive (advent,) fleet supported by an early starbase is much more of a sure bet.
and here is one example: I was playing a game on a single star map (yuck,) on fast settings w/ out pirate raids (gross,) and the player that spawned next to me expanded ala the basic pop. upgrade w/ extractors. So of course they got a much bigger fleet than me as I was trying to build more infrastructure. When the actual fighting started to occur they managed to take out most (60-70%) of my (undefended,) planets and their fleet got (rampaged,) farther and farther away from the (ill defended) HW. But due to the extra infrastucture my empire had had I could build a SB and upgrade it w/ mass disorientation and enduring devotion... and I just built my sb over my defensive structures.
So in the end they ended up wiping out most of my planets only to have me screw them over w/ two sb a handful of illums, some defense vessels, a halcyon, and a mothership. (plus the turrets and repair bays.)
They rushed with HC and hoshikos. Eventually they got carriers too. A buuunch of HC. But the Halcyons boost to weapon damage of a SB over some bare defenses is just overwhelming.