I have just completed week 7 with the Powerbreathe.
At the end of the week I moved up to a setting of 5, still with my 10 breaths at half load, 30 at full load and 10 at half load routine.
I felt able to move the setting up because I was achieving much fuller breaths after a couple of weeks on a setting of 4.5.
My perception is that my breathing has changed since starting using the Powerbreathe, it feels when I am under high exercise stress that I do breath more with my diaphragm than previously.
This has made it less stressful.
I have no measure of how this translates into my performance on the rowing machine or bicycle, but it feels better.