What extras should I insist on in a new Class C

Here's a link to the Atwood's spectacular (if they're reliable) 2-stage propane RV furnaces. If these function as advertised .... then finally someone got it right .... an RV furnace that throttles itself back to 1) maintain a more even heat in an RV with less cycling, 2) produce less noise when running in it's low range, and 3) require less 12 volt power when in it's low range:

http://www.pplmotorhomes.com/parts/rv-furnaces/rv-furnaces-atwood-excalibur.htm