I brew a pretty narrow array of beer styles, but from all the reading I have done a FG below 1.020 is generally considered "expected", excepting some of the bigger beers. Where your FG will actually fall in that range it totally dependent on: % of sugars that are fermentable, fermentation temperature, yeast health, and pitching rate.
So, 1.050 down to 1.010 indicates to me that you had a good solid yeast party going on, and you should be pleased!
In any case, it seems from your post that you have a good adventurous spirit, and solid background knowledge. Don't spend a lot of time worrying about your FG. Ferment clean, age well, taste. Taste good? Hurray! A job well done!