Interesting. I was reading the following thread regarding lounge access and perhaps I misunderstood what the community was saying in that thread regarding intra-Europe travel and access to *A lounges:
Lounges with SAS plus

It might be the case the fast track is truly excluded from Plus tickets. I have been *A Gold for so long that I haven't had to test the theory. So I will take your word for that.

If SK Plus allows lounge access in Europe and nothing else, then the selling point of SK Business I guess is fast track in the rest of Europe (outside Scandinavia) and a free middle seat. You can't use food as a differentiator because both SK Plus and Business are likely to be fed the same meal. It will be interesting to see how they price that out. I don't see those as huge differentiators that would justify more than 20% above the cost of SAS Plus, but that's just me. And if your EBG/EBD, it would only be the free middle seat that is the draw.