I'm working my way thru level I swatches and have about 8 done. So I thought I'd better get going on weaving in the ends.

This Master Knitters Program is so conducive to overthinking what used to seem obvious!

So, I have no problem with duplicate stitch, this is what I usually do anyway. However some of the books I am now reading say to weave the yarn end vertically to avoid contracting the work, another says that on ribbing, its a good idea to whip up along the edge of a knit rib (on the WS of course). And on and on.

Or do I just skip all the other references and go by the "Pesky Yarn Tails" article in the archives?

Just do whatever works. I mostly do duplicate stitch, but when I'm weaving in an end where there's ribbing, I've always used a knit rib for weaving in the tail. As for vertical vs horizontal, I think I usually end up sort of diagonal.

I used to only know how to weave in ends on the diagonal. The MHK program exposed me to reverse duplicate stitch, and then at some point I realized that for ribbing, it made more sense to go up one leg of each stitch in a column of knits (viewed from the WS), wrap around the head of the stitch where I ended, then go down the left leg of each stitch in the knit column. I often combine techniques I have learned in different situations to give me the best result.

For me, the reference books give me a place to start, or a new way of looking at how to do something, and then I figure out which way works best for me and gives me the best result.

There is never only one way or one best way of doing something.

The only reason someone might have a problem with duplicate stitching drawing in is that they pulled the yarn tail too tight as they were weaving in the ends. When I had to do the duplicate stitch for the color change swatch, I actually thought I made my stitches too loose. But they were fine. As long as you can pull your swatch and not see a distortion in any direction, you should be fine.
And the committee doesn't require you to use duplicte stitch unless the directions specify that technique. So weave in your tails by whatever method you feel gives the best look for that stitch pattern. If you want to, you can also include a note on what you did and why.