We are in a 39RKFB! Love it.
Have been full timing for 4 years... We had a Grand Design Solitude up until a few months ago. We loved it as well.
We needed more residential appliances and insulation. Our floor plan before was more bunk house and after 4 years we realized we needed more living and entertaining than sleeping quarters. The biggest factors for us were build quality, residential refrigerator, two toilets and a King bed! Will let you know how it goes but, so far we are in heaven!!!