I ended up taking those worlds after all, because I wanted the Regen Golem and the other two were nearby. I'm moving fairly slowly, so I think I'll break even from the SCLs or at least come close enough that it's not so bad.
Hit all the co-processors and all the data centers. Then I moved up to set up my second beachhead, and attacked that AI HW first (since my fleet was already there). I found a few things during that and in general during the last few hours of playing:
1. I unlocked more Raid Starships. They do the job of getting in and killing things, but I find they're kind of fragile and I can lose them easily. I had reasonable success using my Spire/Zenith Starship fleets (I-IV) along with a Flagship IV. They're slower, but they're also tougher and pack tremendous firepower in repelling things that come after them.
2. I used the extra knowledge I got to unlock Neinzul Enclaves II, III (and IV). They're
awesome. With that number of them, so many drones were spawning that they were clearing AI reinforcements on their own easily and keeping my fleet totally free to attack. The lone Mercenary one I had was good, but it doesn't compare to when you have them in force at all.
3. The core guard posts say they launch an attack if lazy AI is off. I have lazy AI off, and I didn't really notice this. Some ships appeared here or there, but it honestly wasn't terribly noticable.
4. I found my golems of very limited use in the HW assault. Something was pounding the tar out of my Black Widow and I had to retreat it. The Regen golem worked, but it lost health really quickly. The Cursed Golem also seemed to work but it's fragile and I had to retreat it quickly as well... and the Hive Golem gave me a mesasge I'd never seen before when I unloaded the wasps on the HW, some kind of AI response. I decided that was best avoided, whatever it was. Besides, the Neinzul drones were really effective enough that I didn't need the Wasps. (I didn't bring the Botnet at all, that's being used as my primary defense fleet.)
5. I had to retreat back to my fortified beachhead several times before taking the HW, but that prevented my fleet from suffering massive losses. So I'm in fairly good shape now with most of my fleet intact and reasonable resources available to head to the second HW. The AI did try to counterattack my fortified post once, and it went poorly for it. (Millitary III post with a Fortress II and about 30 of each of the mk II base four turrets, 20 spiders, and 2 HBC II's. Oh, and EMP mines. I basically dumped every defense I had left on that planet.)
Anyway... one HW down. AIP is at 354, and with my fleet in good shape I'm ready to head over to my other beachhead right away. I think I've got this one in the bag now. Thanks for all your advice.