I think that the idea of using the leather strops at a degree or tow less than your stones is the result of some of the studies that Clay has done that show the beginnings of edge of the edge convexing with leather at the same angle. One thing that we need to recognize is that Clay has a specific method for stropping. The idea of maximizing stiction and using pressure to achieve (possibly) burnishing seems to be the basis of his technique. The reason the leather starts to convex the edge is that, under pressure, it wraps over the edge. When one uses less pressure, the leather wraps around less. I have been dropping a degree or less with the leather lately, and it seems to be good. For a long time I used the same angle on the leather strops as I do with my stones. That also works well… I I really can’t tell much difference, either under the scope or in use. My technique is to use extremely light strokes and to use the stops in a state that minimizes stiction. I want as little drag as possible. I want to stroke extremely lightly an smoothly allow the abrasives to do their job.
With Balsa there is not nearly as much give as with leather. Therefore you will get minimal wrapping over the edge in comparison. Again I use very light pressure, but I use the same angle on the balsa as I do for the stones.
I think you have to play with this a bit and determine what works best for you, but my theory, and what I can tell with the Veho at 400x it that you miss the edge of the edge when reducing the angle significantly using the Balsa strops.
Bottom line, IMHO, the more give in the stropping material and the more pressure that you use, the more you want to consider reducing your angles.
Phil