Yeah, big point drops on the weekends are the normal for me. My worse weekend was 600'ish, this weekend was about 250... but overall, I'm numb to the weekend stupidity now.
I tried ACC for the first time this weekend, and I can say the tire model is better than iRacing, but I still feel iRacing is the better overall sim. As far as iRacing's biggest issue (to me), the tire model, ACC feels a little too grippy over the limit, iRacing feels too slick anywhere near the limit... a happy medium can easily be had somewhere in the middle. I still prefer the less sophisticated graphics of iRacing, as well as the feel of iRacing. One thing that stood out to me was the braking experience. iRacing is second to none, at least that I've used, in this category. ACC isn't bad, but is definitely a little wooden in comparison. FFB on both are good. I thought the pitstop implementation on ACC is a little clumsy, but I'm sure that will get better with familiarization. All that said, most of my GT racing will still be on iRacing.