Indeed both of those places are well known in ports with good infrastructure and are widely considered reliable.
HOWEVER, in this and any other case of booking with an independent vendor, it is ABSOLUTELY VITAL that you have written confirmation of their exact cancellation policy in advance. It varies widely around the world, and from vendor to vendor. Do not depend on a message board or forum or any other place to answer this question, get it in writing from the vendor.
It is also important to know what the policy is if the ship is delayed but does make the port. Will you get a refund, will your tour be shortened, will the operator cancel? Be sure you know.
I have seen many many posts from people who did NOT do that and were sadly surprised.