I also started out with the scale from the Lee kit, but I knocked the balance beam off the bench onto the concrete floor and the poise slide popped off. I could never get it properly calibrated again.
I can't speak as to its accuracy as I never tested it with check weights, but things I found helpful were;
1. I agree with Cerdan, you need to have the "main line" on the poise centered on the .1gr increment you want, and an "equal amount" of white showing on the .1gr increment above and below what you want. This gets a bit harder if you're trying to weigh a charge ending in .9, .0, or .1 due to the "wrap-around".
2. It's sometimes hard to get the poise centered where you want with the light available. I have a gooseneck lamp with a 100W bulb on my bench, and would shine the light directly on the poise to help the process.
3. As you remove the pan after weighing a charge, the beam bouncing around would result in the poise wandering off your setting value. If you read the manual, there is a little push-in tab on the back of the poise that locks the poise in place. If you lock the poise in place this won't happen and you'll get a consistent charge weight every time.
This may be opening a can of worms, but what are thoughts about how level the scale is impacting accuracy or consistency. My bench is very stable but not exactly level.