From what I've seen, the change in model year is a non event. They tend to make the big changes later in the year...July/August. They will make subtle changes it seems, whenever the mood strikes them.
When we were researching before buying our current camper, there were 3, distinctive versions of the same model called 2010 production...early model year (Mar - July, same as previous year), mid year (Jul - Oct), late production (Oct - Feb). We had the dealer check with Rockwood whether any changes were planned when we placed the order...there weren't any.
They have a disclaimer on the order form which says "the customer agrees to accept final product regardless of minor modifications to layout, specs, colors or option types within reason while in production".
At the time of the purchase, we asked a lot of questions based on our research, to fully understand what we were getting.
Nights camped in 2013 - 55, 2014 - 105, 2015 - 63