I've been running incentive/content locking offers for a while now and here's what I got:
CPALead was the first company I tried (first time I learned of content locking) and had pretty good success. Cross tested with Adscend, epc (which is my measure of how good the network is) was about the same on both networks.
Next, BlamAds appear. I give them a shot and saw my epc rise by about $0.04. Cool AM's.. still use them for some international traffic offers.
More recently, joined AdgateMedia - new incentive affiliate program - and they have the highest payouts, hands down. Saw my epc rise another $0.05. Smaller selection of offers, but more get added often. I even requested an offer and it was live within the week.
and yeah, pretty sure the adult cpalead (adultaccessnow) flopped. Site says beta testing is done and doors for new registration are closed. They only had like 2 offers when the site was live.