I don't seem to come across DD or 6 deck games with Surrender and S17 or even just Surrender or just S17. Perhaps they are offered in HL rooms? I play mostly in LV, MS and MO.

Have they declined in numbers in recent years?

I started skimming over BJA and maybe 50% of the tables and significant space is dedicated to games with Surrender and S17. I suppose I would pay more attention when and if I end up in a place where such games are available and prevalent.

I am amazed at how much I still have to incorporate in my game from BJA I started dog earing pages in BJA for further studying and memorizing. It's just been 3 days since it was delivered to me. Don S spends a lot of it explaining how various stuff was calculated and arrived at, stuff I don't need because I believe it when he says it, no explanation needed. So, finding and marking the conclusions, learning the end results and not how they were arrived at is my task.