I was just on the Maasdam on March 24th. I have almost 100 nights on HAL. The Maasdam was a beautiful ship with excellent food and service. We loved our experience on rhe Maasdam and had no problems as the ones you described.
The Noordam (we have been on it twice) is the ship in need of some TLC the most. It is my understanding that the new Oosterdam will replace the Noordam in Europe. I am assuming the Noordam will be 'retired' by HAL and show up as a COSTA ship in the Carnival inventory (or be sold to another cruise line).
You made an excellent choice selecting the Maasdam. I am sure you will have a very enjoyable and trouble-free cruising experience.