I'll chime in here on the Propane Buddy Type Heaters compared to an Espar/Webasto.
Had a Buddy in my full sized camping van. With the Buddy the windows and interior accumulated condensation at night, uneven spot heating and open flame in Van. Always worried that I'd die or have brain damage from fumes :)
In our current small Class C sized Rig have an Espar. Huge cost difference, Espar ran $2,300 for a professional install. Runs off the MH diesel fuel tank. I too didn't want propane. Very even heat, can maintain any temp in MH irregardless of external temp. Compact design with adaptable interior vent kit. No vents show on the outside of our Streamline Rig.
IMHO Bob is one smart cat and knows his stuff, he made the right choice by scoring a great deal on a second hand unit.