Yes, using the slider does help. Even for me. If I feel really good about a post, I upvote it 100%. If I'm a little "meh", it's a good post, just it doesn't have the full force behind it, I go to 30%. If I'm on the fence.. I see the value, and think it should be voted, but I don't want to cheerlead it on, I give it 50%
So my mood greatly affects my slider. Each time I slide my slider, I'm kind of waiting for someone to call me out on my decision, which I could qualify each time if they did... but luckily no one does that.. and I don't have to.. :)
The slider is something that may be key, I agree. good post.