Problem: Each like loses increasing values as you get more likes, and each dislike loses increasing values as you get more dislikes.
On the surface, this seems like a good logic, but here's the problem. 500px forgot the relativity of the votes.
Once you get to a score of 90, the impact of a Dislike is so high. You can lose 6 to 10 points on a single dislike, and by then. Since your likes are so devalued by then, you need at least 20 more Likes to regain your momentum. By the time you regain your momentum, the time decay drops your score by 11 points anyway.
Make Dislikes votes more relative. Instead of giving the first dislike so much value, why don't we have the first dislike go down relative in value to the previous Like. So if your last like added 0.5 points to your score, the next dislike will take that away.
This is much more Directional, and it makes sense.
I am not against the Dislike button, but the underlying scoring logic is no good. I love 500px, and I hope my suggestion can help this site improve and maintain its community.