I'm not too familiar with burnishing and haven't done it myself, but I get the gist of it. From what I understand given Reed Gray's writings, the rolled edge is necessary for clean, high-angle finish cuts. To be honest, as a noob turner I didn't waste many brain cells thinking about this cut, but the more I do it the better finish I get. Haven't had to use 80 grit in a while!
I haven't noticed much difference in my round-nose scrapers whether I sharpen the tool with the top up or down, but I don't do a separate burnishing step on the edge. I have noticed that the tool loses that edge rather quickly which has me thinking about burnishing rather than sharpening every few cuts and maybe make my tools last a bit longer. What is your process for burnishing, what tools do you use, how often, how much, and does it take the place of high-frequency sharpening?