Yes, I have done a lot of ash with narrowed backs. Mine were all "pyramid" design. I was pretty convinced that narrowing the back was the best approach, but time and more bows have mellowed my view.
Especially with the "pyramid" design, the grain runs off both edges of the tapered limb. I had several disappointing failures near the tips with the back ring lifting splinters at the edges. Now, I don't feel it is useful to strongly narrow the backs of bows.
The gain in narrowing, cutely called "trapping," is in reducing limb weight. (Balancing tension and compression strength turns out to be a pursuit whose value is uncertain, much as I liked the idea.) The tips are the area where weight reduction would most benefit performance, but they are also the area where the edges are most likely to lift splinters.
So, at this point, I am no longer confident that trapping is very useful, unless you are trying to catch a coon.
Jim Davis