We have a bit of a different situation because I have many more days in the shop and a more obvious diagnosed problem (might be fixed, but things keep popping up with this truck). I totally feel for your situation, though. I was actually planning to do some mods on my truck too, but the problems started so early that I never had a chance to do any of them. Once you sink that much time and money into a vehicle, it's definitely harder to get away from it. I think there is a chance they have to reimburse you for add-ons to the truck (possibly if they were added within a certain timeframe from when you bought the vehicle), so check into that if you end up qualifying for lemon law buy back. That probably varies by state. At this point, I'm really hesitant to add anything or make changes because I don't want to throw money away on a truck that won't last or I will need to return / trade-in soon. So I'm basically in this holding pattern and feeling almost like it's a leased truck because I don't want to do anything to really "make it mine" due to the reliability.
I think I'll wait until I hear about an offer to decide what to do. I don't think I'm going to keep this truck long term, but I'm not sure if it makes sense to keep it until 2022 models arrive if I can get a good settlement. The issue with settlement I think is my truck has probably depreciated so much just because of the high initial cost, repair history, and a couple dealer add-ons (basically I paid a lot), it will have to be a big settlement to get to the point where it's equal to a buy back / refund. I'm not sure how big GM goes on the settlements. The other thing that makes me nervous about the cash settlement is what happens if it continues to have problems? I'll be under warranty still, but there is no way to just get away from the truck at that point (besides sell / trade-in assuming it can be repaired adequately).