I'm sorry- I made a couple edits to my post but I couldn't figure out how to change it in the original post I made!
I like draw reins as a complimentary tool in ADDITION to my regular reins, that is my BIGGEST pet peeve, when I see people riding in draw reins as the ONLY rein :/ If they don't become a crutch, they can be a valuable tool. I think this is where people go wrong with them, as you said, they use it as a substitute for time and patience.
That being said, I had a horse that for his own benefit, REALLY needed a gentle reminder to relax his frame. He was SO SO SO upside down, it would have been really easy to crank his nose to his chest and hold it there, but it would not have "fixed" him at all. He learned how to evade the bit form a previous rider, but was very un-balanced so small circles to get him to give to pressure and drop his nose would have been a little counter productive. After talking with his vet and the chiropractor (who is a vet), I explained how I wanted to use them to start to encourage him to relax into a frame and lower that head- he was pretty sore in the poll and back as a result of not knowing how to relax. He had months of groundwork before I got on, and many chiropractic sessions. Knowing that it takes YEARS to develop a good topline, the draw reins were used as a gentle reminder, along with leg and seat aids to get him engaged from behind, to start to relax down and round his back. They worked beautifully, but I used them ONLY when he was relaxed- I do not like fighting a horse with draw reins because I think in a lot of situations it ends up creating MORE tension, which can create more problems than you started with. Along with arena work, he did lots of "hill work" to strengthen his hind end, back, and stifles- arena work alone would not have been enough. Just my thoughts on them, it sounds like you've done your homework and know what you're doing!