I've been wondering if this could be made up in knits ever since the pattern came out, and last night I tried it. I think it turned out pretty well.
I made some changes to the pattern to make it work-
For the front and back yokes, I rotated the pieces 90 degrees from the grain line, so they would not have much crosswise stretch, and would behave more like a woven. I considered interfacing the back yoke pieces, but didn't end up needing to. I also did two lines of stitching, one for putting the pieces together, and another for stay stitching the neckline.
When I attached the yokes to the front and back panels, I serged the seams, and treated the yokes as one piece. After that was done, I ironed the front panel up, toward the yoke, and then top stitched it, so it wouldn't spread.
For the shoulder seams, I rotated the bias piece 45 degrees, so the stretch would be on the shortest side of the rectangle. Then I attached it normally. I was worried that if I cut it on the bias, it would spread a bit at the shoulders.
I hemmed it the normal way, but next time I might use my double needle just for kicks.
My daughter loves "softies" and will pick them out of the drawers first, so I'm always looking for ways to adapt patterns for use with knits.