With the current economic climate in oil and gas industry what every certs you hold will not matter due to the amount of projects planned for 2015 .
As far as Rov courses go its not a mandatory requirement , if you wish to spend money on courses then why not do electronics or hydraulics .
Just spend time and go through the archives on this site under the main header of ROV Rookie Corner many questions you may have the answers there .
But now is not a good time not only for Rov personnel but all offshore personnel , There are some work available if you have a 1000 hours plus on Perry , UHD or SMD systems but very other little requirements .
Good Luck