About Cartaxi, check it on here https://bitcointalksearch.org/topic/ann-cartaxi-special-signature-campaign-updated-2174287 They just started their bitcoin campaign, so they still didn't pay anything since it just started 2 days ago.
If you were joined on their bounty campaign which will be pay with their token, it takes longer time than bitcoin (Ussually within 1 month after their ICO ended)
Thanks for useful information but i see that best signature bounties wich will pay by BTC they only accept membes who have high rank on this forum. As Cartaxi only accept Full Member/Snr Member and Hero Member/Legendary Member