The only thing I might suggest on this tutorial is in your side note, try and make it a little less 'personal.' Instead of saying I prefer 90/10, perhaps use a different approach like:
If you would like the most flavorful tasting burger, try using 80/20 so you have the right amount of fat and burger to give you a savory taste. If you're more of a health nut or just don't like a lot of ooey-gooey fat, the grade of preference would most likely be 90/10. 75/25, though not recommended, would be for those fatty lovers who love the dripping mess that is sure to leave your arteries wanting more. (or something along those lines)
However, I thought that this tutorial was very well written and thought out and I may just have to give these burgers a try. Nicely done.