Firstly, congratulations on your new grinder Mahalia.
Secondly, I use a BNZ grinder with a dosing chamber, grind on demand, and use my eye to estimate the grams, but more importantly, watch what happens with the pour. As for grams, Ive checked and am consistently within .5gm for every double, so your theory doesnt weigh up (pun intended).
As for wastage, I spill about 20gm per 100 doubles. I can live with that. ;)