I had the opportunity to see one of the new Sporsters yesterday and a first view of the rear sight. It looks just like a typical rear sight for a Marlin .22. Its dovetailed into the barrel and has the elevator adjustment. Also, the receiver is drilled with three holes.
I thought it looked rather "cheap" on a Sportster. Perhaps it was that I'm used to seeing the typical adjustable rear sights on the NEF's. The dovetail sights are pretty much the norm on most .22's. It just seemed a bit odd.
I probably wouldn't let it stop me from buying one, but I am glad I have the "old" Sportsters in both .22LR and .22 Mag.