Based on my experience it will be the 380 bar. I put a 380 wide bar on my BH G6 and found the same thing. Really twitchy and unstable when on the hoods, particularly descending. But when in drops was a lot more stable, and narrower so had the aero benefits for that.
I got a 380 for my Hygge build but haven't yet built it up as I'm stuck in a sling from shoulder surgery for another 2 weeks yet. Good thing about hygge bars is it's is 380 at the top and 400 in the drops.
Do you feel more aero with a narrower profile? Noticed any speed difference on solo rides?