Agree that one of the BIG drawbacks of the Haven are the non-changing menus. The "accommodating beyond the printed page" maybe 'depend on the ship' thing. We did a B2B last October on the Bliss (Haven on both), and they were not accommodating at all for any changes. Just trying to get a plain salad in the Haven restaurant seemed to be a bit of a challenge. But with the YC's buffet offering on the pool deck, there are multiple food options to choose from.
Maybe if more (or any?) of the NCL Haven offerings had the equivalent of the YC buffet on the pool deck it may have been a different thing. But, that was not the case for the Bliss. Thankful that it wasn't since they were October Alaska cruises and being outside in general was a struggle. Don't get me started on the Bliss's Haven smoking area.
We are basically the YC/Haven cruisers that don't leave the comfort of the YC/Haven once we enter. We may do a show every few days and except for heading to the spa for a massage, we stay put. We enjoy being at sea - we enjoy being pampered - and YC does that for us. Heck, we don't even need to leave the YC for evening entertainment with it being provided in the Top Sail Lounge. That is one of those things that is a huge miss for NCL in our book!
We MAY need to alter that choice with our upcoming 25 day TA next April. But, we'll see how it shakes out.