I do not consider HUET, EBS nor rebreather to be a joke. EBS has the longer duration but must not be deployed to early in order to exhaust the duration before splash.
Sorting it out when already upside down is theoretically possible but I think it is a remote possibility (also considering cold shock gasping in).
What worries me is that the EBS is still a dry training (in the Netherlands?) with indefinite duration. The HUET is still a rebreather course. (I would be extremely happy to be corrected, my knowledge dates back 2 years)
Self Loading Bear