Daz , you really don’t like anything Chinese do you
It may be a cheap heater but it works in exactly the same manner that yours does , little drips of diesel fall onto the glow plug /screen , if a unit should catch fire the first thing to go would be the circuit board, this would cause immediate shut down including the fuel pump !
Everything else is metal apart from the heater casing which funnily enough is heat proof !
With regard to the exhaust , that has always exited through the van floor , again the same as yours!
The little bit of fume escape I had on early models has been addressed with the use of V bands , CNC machined for a perfect seal , they use these on vehicle turbos which leakage would not be acceptable!
So the only real difference is a massive price variation and the fact that yours is ( Pro fitted )
Water in water out , diesel in fumes out , power in , it isn’t rocket science mate
I do think the way you see things is that if it doesn’t cost a lot it’s rubbish