I've been working on my Tessa fairly steadily, and this weekend I bound off for the armholes. The designer recommends a "bias bind-off" for the armhole decreases which really is a good technique for this application. I don't typically recommend slipping any of the stitches on edges that will be seamed or along which you'll pick up stitches, but when the bind-off is the final work done on that edge, slipping those stitches gives a very nice effect. Commonly referred to as the "sloped bind-off" this technique requires that you slip the last stitch on the row prior to the bind off. You then turn your work, slip the first two stitches and then pass the first stitch over the second stitch and proceed with your bind-off as usual. Since the bound off stitches have not been worked, there is no little bump at the end, and the finish is very clean and smooth. Here's a close-up of my armhole edge.
As I mentioned, however, this is not a very good bind off when there is seaming to be done, or stitches to be picked up along the bound-off edge, so resist the temptation to use this bind off in every application. Why? because when you don't work the stitches that you bind off, you substantially reduce the places in which you can pick up stitches or make a seam. Each time you work a stitch, you create several small places to insert your needle and make a smoother picked-up edge.