Though the posts are competitive but its of no use for active members of the campaign as you have a maximum of 50 posts a week.
There are many other campaigns which have no post limit.
I want to give you a suggestion to make it to a fixed payment weekly rather than per post. If you want to pay per post than it would be better to pay highest as compared to other campaigns like- DaDice and Bit-X.

Good Luck,
-Rony