I'm too lazy to read through this thread... but a good tip for weighing RCs: Take an empty gelcap, weigh it, do this three times and mark down the weight. Average it out, you have your gelcap weight. Open the gelcap, insert powder until you think it is about right, weigh it, again with the three times method.
I do this with my Gempro. And I've not had any problems. The MOST a reading has ever been off, was 4mg, but that was fluffy substance, and after letting the scale sit a couple seconds, it finally balances out.
I *LOVE* my Gempro and wouldn't really have it any other way!