I would go fat cap down in a WSM. I am not at all sure it matters anymore.
The problem with pulling at 190°F and wrapping in foil and coasting, is that it might well work out sometimes, but, not always. It relies on a couple of factors, one you can control (internal temperature) and the other you can't (meat composition).
For instance...I recently had a cook of a CAB brisket, it was very well marbled and floppy. All indicators were that it was a perfect brisket. I cooked between 290°F and 315°F, it took every bit of 4 hours to hit the stall, and another 6 to push through it. Then it climbed very slowly to 200°F, and it was not at all done. At 14 hours, at high heat, it gave up the ghost, at nearly 215°F. It was juicy, tender, a perfect cook, except is was 9:30 p.m. That brisket would never have made it if I pulled at 190°F.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"perhaps...but then again...maybe not..."