The ship has been drydocked more than once to fix this problem and I think the answer is that it may always be somewhat of an issue. I do think they have improved it significantly from when it was at its worse.

The varying reports depend on so many factors. How the seas hit the ship on that trip and how people react to the vibration when it is prevelant. You will have people who say it was intolerable, you have people on the same trip say no big deal it was worth it for the balcony. They can have cabins right next to each other. Ships at the back as rule have more vibration and movement. Just as a note of interest the Mariner is one of the smoothest ships I have ever experienced at the back.

I think you must recognize that you may have a vibration issue when you take a Horizon suite. If that concerns you move to another cabin. If you really want that big deck and you can handle the vibration if it comes stay where you are. You have the choice.

I was on the ship in August, during the only rough night we had I went to the back and stood on each corner of the ship on every deck.I can honestly say I felt no vibration at all. However, I would not take that as an absolute indication that you wont have some vibration on your trip.

I was in the dining room on my last trip. The person I was eating with said "oh this ship is moving so much". I have to tell you it was not moving at all. I looked at my glass of water and it was completely still. This is the problem. One person is hyper sensitive, but to them they dont see themselves that way. Others the ship can be rolling all over the place and they are happy campers (thats me). With this variance of sensitivity you just have to look at yourself and be honest with how sensitive you really are and make your own decision.

That does not give you a definitive answer but you wont be able to get an absolute answer to this question.