I'm so sorry to say this, but we have done both CRT and Akershus, and we thought that Akershus didn't even come close to being a substitute for CRT. Now I'm willing to accept that perhaps we hit Akershus on a bad night, because others rave about it, but our experience there just wasn't super-special.
Nothing compares to dining in the castle, and while the food is mediocre, we have always had spectacular character interaction. My daughter, who loves the princesses, especially Belle, begged to go back to CRT for her Sweet 16; we did lunch for the first time last trip and thought it was just wonderful! I might give Akershus a very small edge where food is concerned just for a larger variety...but nothing was particularly great there either.
We are looking forward to trying 1900 PF this time for a little bit of stepsister mischief.