No... Make it absolute clear...
Previous Pay Later: Hold fare and seat for 24 hours for free for everyone
"New" Hold your Fare: Hold fare and seat for 72 hours, a fee for non member, free for MPC
The usual seat reservation for MPC elites: Hold seat only, up to 24 hours before departure for DM, but need to call... Fare price is never hold for seat reservation... Like if you reserved a seat now for a flight departing March 2018 and CX increased the fare of your booking class say in November 2017, you need to pay the new increased price if you ticket it in say January 2018