Re 1. That makes a lot of sense now. My intuition is still leaning towards trajectory change interacting with XRR for the reason that maybe the best ways to reduce x-risks that appear after 500+ years is to focus on changing the trajectory of humanity (i.e. stronger institutions, cultural shift, etc.) But I do think that your model is valuable for illustrating the intuition you mentioned, that it seems easier to create a positive future via XRR rather than trajectory change that aims to increase quality.
Re 2,3. I think that is reasonable and maybe when I mentioned the meta-work before, it was due to my confusion between GPR and trajectory change.