I get good shaves from Gems with my normal DE grip. I'll have to give this grip a try and see if they get any better.
What I do for the under the nose is what I do when I shave with a straight. You kind of scoop with the razor in a downward stroke towards your lips. You can find it in any forum on Straight razors, such as the Wiki on straightrazorplace.com. I never do ATG on my upperlip, only WTG and XTG.