Just a quick follow-up:
I've received my first order of 3 meters (the 300V AC ones).
Here's the close-up of the movement.
And the innards.
As you can see, there are only three components inside:
A diode, a 180k resistor and a 47uF cap (only 25V rating!?).
Iron is stationary, coil is moving.
Anyway, not being a particularly patient guy, I started messing with one. I hooked up 12V DC and the needle budged a bit, so I dropped the voltage to 5V, took out the 180k resistor, hooked up my decade resistor box and ended up with 5k5 resistor as being adequate for the job. Not having one at hand, a 4k7 + 1k combo turned out to be a suitable replacement.
Measuring the current of the modified meter, it only draws 0,7mA at 5V (full deflection), so that's good news.
A simple PWM sketch shows linear behavior.
All in all, I find these quite promising. Disassembly is easy (only two screws holding the case together), modification is trivial and cheap. I think I might like them!