[fuzzy]

When you walk you don't hurt so the disks are not causing pain.

There are cases where then motion of the ADRs are exactly the thing you don't want and that may be part of the failure rate with ADR surgery.

Putting the DSS in is supposed to limit or stop the articulation of the ADR so that when you sit the ADR at S1 does not get articulated which may be where your sitting pain is coming from. It articulates more then your natural disc and that may be why you have more pain now then before surgery. Based on what I saw on my own rays it is surprising how much motion the ADRs allow and I am glad in a way that I got fused at S1. Dr. B might think that limiting motion of the ADR is the best strategy as the ADR itself is not causing pain as you have shown by being able to walk!! Another Dr. might think to play it safe and stop all the ADRs from moving to much...
I personally agree with doing the level that hurts, not more.

I don't have your answer for you but I feel you should not take out the ADR if it is not causing pain but find out exacly what causes the sitting pain which may just be the excessive articuation of the S1 ADR. A good bet is the DSS. If you still hurt after that surgery, don't give up, there is an answer. but you have a good chance of much less pain.

I am not a doctor, just a patient who works a life of advanced troubleshooting.

Don't take out the ADRs...