Well, since this thread has bubbled up to the surface...

I plann on redoing the curved cutaway a bit; they aren't quite as smooth of a curve as I would like.
I raised those sewn down areas in the back, at the top of the vent pleats, up a few inches. They are now sewn down between the shoulder blades and just below the top of the kilt. The darts at the top are smaller and the jacket fets even better at the waist line.

I have looked into ways to do this on the corduroy jacket but with a more tapered pleat that will not need to have the three inch sewn down area.

I have also been looking into ways to refine the seam on the experimental jacket so that it is much more like the regular seam that has been sewn from the inside. As it is now, it is sewn down with small invisible hem stitches a bit like on a kilt fell.

When I work these things out, I can apply them to the formal jacket I am planning to convert to a kilt jacket.