Usually campaigns with a history of payouts pay a bit less than new ones that want to attract people, but at least you won't have to worry if the payment is coming.
Bad time is ahead if Stunna switch to fixed pay and push the referral program. A lot of time people check the name here and directly go to the site without clicking the link. At referral program, campaigners will lose that referral amount and that may be significant.
By the talks in the Primedice thread, he is thinking about keep the pay by post for few selected user, and make the others use only the referral. This makes the fixed payment looks better
The fix rate is actually bad cause he will be paying more for posts then get less exposure, 0.1 a month for 50 post is 0.002 per post. And all you have to do is buy shill accounts
0.002 per post for fix rate get you reasonable exposure.
There are a lot of people abusing PD signature campaign and Stunna end up paying a lot more for marginal increase exposure.
Yes, there are missuses, but exposure is exposure, and i doubt hes in a loss with his campaign.
Also, i dont think its smart for him to change his campaign terms too much, because when people leave his campaign, their sigs in all posts will change.
There are alot of searches that include old posts/topics, and it would be a shame to loose that.
From what I heard of, Stunna has been paying 20 btc a month for the sig campaign.
I don't think he is in a loss, but the advertisement effect wouldn't be high as most of the people on bitcointalk has already heard of PD.