Laura,
I cannot hope to tell you what meds would be best, or which way to go, but I have two comments to make.

The first is about your CR - this formulation of sinemet does not suit everybody. I was on it for ages, and only realised when I came off it that I was actually quite undermedicated. For those it works for it works really well, but for some like me our bodies/brains do not absord it properly. So the change to ordinary sinemet makes a huge difference.

The second is about Comtan. I would disagree about only getting half an hour extra benefit from this. Perhaps others can confirm this. I go a lot longer, and over time have found that my off times, with the exception of going overnight unmedicated and the usual morning issues, are less off than before. The difference between before Comtan and how I am now is huge...

If it were me I would try more options before resorting to surgery, it can take time, even a few years, to find a good meds regime and from the sounds of it your symptoms are controlled quite well, just don't last long enough...

Good luck with whatever choices you make.

Lindy