Personally we don't find the weed gun even kills weeds properly - I think it highly unlikely it would have a have effect on moss.

Hi Robinfrance,
Why not do the high pressure water gun,
Ive a pool and patio plus verious statue and larg urns and all of these have had the p/gun on them only last week,
they came up good,
the pool slabs at one end "phontinia robin hedge behind "
tend to have more shelter and moss grows there, the gun just removed it in seconds.

I got my gun from the local "BRICO" its not the largest one but is worth buying and can be used for the under side and wheel arches of the tractor/car.

The flame guns i found removed the top growth but with some weeds seemed to do little if anything for the roots infact they grew stronger.
One more point ref flame gun's,
If used on the bedding area's the heat burns the goodness out of the soil/compost in the area your burning.