I can only be satisfied with diesel heating and would not go back to gas.
As I said, I have had the Webasto Dual Top for thirteen years and the Truma 6DE for almost four years.
With the Webasto I reached -20°C, with the Truma (for now) only at -4/-5.
Some people complain about the noise, comparing it to a jet taking off but perhaps that only applies to truck heaters.
The Dual Top made a bit of noise in the first few minutes when it had to reach the set temperature but it was mounted on the outside and you couldn't even hear it inside.
The Truma makes exactly the same noise as the gas one, mine is under the bed and you can't even hear it.
Once the set temperature is reached, both "modulate" and maintain it without problems.
Diesel:
Consumption is minimal, with a full tank you could last for weeks.
Batteries:
Except at the moment of ignition (10A for about two minutes, perhaps even less) it is equivalent to those of the gas one.
With two 80Ah gel batteries and the stove turned on 24 hours, two days can easily be done, even saving a little on three.
Gas and underslung tank:
In some countries this could be a problem. In France Total no longer sells it and probably some other brand will join.
In Italy (manned refueling only) the tank must be written on the vehicle document and at the pump refillable cylinders are prohibited.
In Finland LPG does not exist.
Then I don't know how many other nations have some supply problems.
EHU:
Both gas and diesel Truma has two powers available (900 and 1800W).
The first is sufficient only when the external temperature is at least ten degrees centigrade (good for reducing consumption, either gas or fuel)
The second could be too much in most campsites and rest areas.
Max
p.s. A large number of brands now offer the Truma 6DE as an option or, increasingly, as standard.
See for example the latest version of the Hymer Grand Canyon S which does not include the gas version.