On my Seranade Panama Canal cruise last fall we had both. I had a crab appetizer that was was real crab in the early part of the cruise. Towards the end of the cruise, Steak Oscar was on the menu, described as being topped with crab, it was not, it was surimi.
I don't mind surimi, as long as it is billed as surimi or immitation crab. I was very disappointed in the Steak Oscar and would not have ordered it if the description had been correct.