The back bevel does help on a standard stanley blade, but a thicker
iron is, as you have found, a great help as well. I finally got around
to flattening the back of my veritas A2 2" blade and replaced a flaking
SW era blade. When working with some purpleheart with two reversing
streaks in it, both will still tear it out. Neither will make it
perfectly smooth. It takes a scraper to finish it off.
I also have a Steve Knight smoother, it takes only a few minutes to get
it figured out, they are awesome to use. I learned the fingertip
method Steve talks about, I even got to meet Steve in his shop and feel
what he was teaching.
With my finger tips keeping the blade just a touch inside the body, I
set the wedge. This causes the blade to drop down just a bit below the
surface. A couple of tries and I have it set. Although I don't own
one, a small brass blade adjusting hammer would be beneficial. I
currently use a hard plastic hammer which I have to whack pretty hard.
There is a second blade I have with a back bevel I bought from Steve (I
put the back bevel on it), but I have not tried it yet on that piece of
purpleheart. Might give it a go today.
After the smoother I bought the scrub plane. The chips can really FLY
out of that one!