If you have no interest in diesel then consider keeping your LR4 and getting an extended warranty.
I LOVE diesels and agree the LR4 should have had one in the US...problem is that if I wanted to go this route, I would have needed to order a Disco many months ago. My dealer only orders them with stupid options such as "intelligent" folding seats and other stuff to appeal to the "I'm almost driving a Range Rover" crowd, which is the typical NJ buyer for these vehicles.
Quick update: in the end, my dealer offered me a 2 and 3 year option for CPO. I chose the 3 and figured I would be in for the long haul (which I'm happy about). I thought $3k was reasonable.
I'm less worried about the issues I initially reported now that I have some insurance. Also, was so happy to get back into my LR after a few days in a Disco Sport loaner...it would be really hard if I ever have to go away from air suspension.
Thanks for all the feedback.