I worked for rccl as an assitant systems manager.
The benefits of the EO are:
Much bigger cabin
Much better contract duration 10 weeks on 10 off, vs 4months on 2 off if you are the IT manager or 6/7 months on 6 weeks off if your are assistant systems.
Much better pay
Better working hours
You are in Marine department vs Hotel so you get other benefits that hotel dont.
Downsides I cant comment on as I didnt do the job.