I think it depends a bit on what you're locking and which countries you're targeting. High quality content will always get higher amount of conversion. Different countries may pay different amount of money on both networks.
adscendmedia also have international offers, so even if i target usa traffic, there are still offers for the international viewers and in this way i can also earn on them. with leadbolt and cpalead if someone enters out of the usa he or she gets the message: "offer is not available in your country".
noob lol cpalead and leadbolt Geo Target and have no problems with international, cpalead is probably the best international content locker out there....there US is okay, not the best, but its okay... sometimes I send my US traffic to my own offers then send the international to cpalead