If people are given a chance of either dying or having an arm amputated and replaced with a high-quality prosthetic limb, I'm having a great deal of trouble imagining people who will choose death, all else being equal.

If the question is between losing all four limbs and death, it becomes a bit trickier. Being a quadruple amputee is a big drop in quality of life with current prosthetic technology, and if no prosthetics whatsoever are going to be available, people might justifiably choose death instead. But we already have good enough prosthetics for the below the knee/elbow case that I wouldn't hesitate to take the amputation then, and it shouldn't take unimaginable technology to provide reasonably good complete limb prostheses.

I imagine most people haven't worked through such an extrapolation into the case of a brain in an entire prosthetic body. Will they still keep the aversive intuition if they do?