[sharman]

I surely know nothing about fusion. When you ask if you are 'too far gone' for the newer technologies, obviously you're not talking about the levels that have already been fused, right? I would say, if these new technologies bear out, there's a good chance they will save you from having more fusions, if another level starts to deteriorate and you treat it in time. One rule of thumb for the nucleus regeneration/replacement is, you need at least half of your disc height still.

I'm also no help about the hardware and your metal allergies. One thing does seem worth considering. If I'm correct in this understanding, the hardware is to keep things in place while you fuse. Once you're fused, you don't need it any more. So, given your understandable concern about the metal allergies, perhaps you can plan to have the hardware removed at the earliest opportunity. Of course another surgery is always risk,there's scarring, etc. But it's an option. Wonder what you could do to find out if you are having a bad reaction to the metal. Are you not recovering as expected from the fusion?