Slope Meter

Never used one, but I was thinking of putting a slope meter on my D6....something like this: http://benchmarksupply.com/cart/slope-meter-no.1.html Do you prefer to mount them on the back of the blade or on the dash? Dash would be easier to read but would it be harder to maintain slope? Blade mount would be more prone to damage but looks like you could make corrections quicker. Do you have a favorite model? The No.1 slope meter shown indicates from 0 to 2:1 Don't plan on dozing anyting steeper than that (hopefully)...mostly need something to either keep me on a specific slope or for grading level.