Got a question for ya, I want to buy a brunton 9077 compass, which is the military style with metal casing. There's also the fancy looking 8099 which is six time the price. Or pretty much any of their plastic lensatic (8097, 26DNL, 16DLU etc.) cost more than 9077 does. Does those plastic ones work better? Or are they more expensive just because they are newer design and such?