I'd 2nd the PACT
I have one...accurate to .1 grain If this one is good to .15 grains, I'd think it would be good for rifle. I suppose I'd check it regularly to make sure it's consistent.
As to the accuracy question, you can spend thousands chasing that ghost. If I'm working up an accuracy round, I'll vary powder by maybe .2 or .3 grains. Again, depends. If you've a Weatherby mag that holds 80+ grains of powder, changing .2 at a time would be a slow process. Changing .2 on a 45 acp with Bullseye might be too much
The longer I live, the more I see people do things to get themselves hurt. The more I see people hurt, the more cautious I get..... YMMV