Measuring VTF with electronic gauge....

Same here. The acid test is you take the tare weight used to check the digital scale and put it on the Shure. Or any other known weight. Then if necessary tweak the Shure to zero it out and you will know the correction factor. The Shure can then be used with just as much accuracy as anything. 

No, but the pot shops here in Seattle sure are. So what I do, buy a gram, put the green bud on the Shure, zero it out at 1g. Transfer weed to bowl. Drop the stylus, adjust VTF, light the bowl. Very important these be done in that order. You can trust me on that. Barts will vouch for me on that. He keeps his Zerostat in a walnut case with a lid.

What matters is that VTF be measured with the stylus at the same level as when playing a record. Some arms because of their design can cause VTF to change as the angle of the arm changes. So in other words you want a gauge that works like chakster said, with the stylus at LP level. Not LP level plus the gauge. LP level.   

VTF btw is always specified as a range. Anything within that range is perfectly acceptable. Within that range however VTF is set by ear. If you like it at the high end of the range then that is the "correct" VTF for you. Precision therefore is only a factor to the extent it keeps your "by ear" setting from being too high or low.