I've done some more testing (all 10 to destruction, got some more though 
)
They have pretty low torque at all voltages, though they probably won't need much for the sort of micro projects you would consider using these for.
Their biggest limitation (for me anyway) is their coarse step resolution, maybe only 8 steps for full 360 rotation.
This makes sense I suppose, given that they are from camera lenses originally; I'm guessing its for f stop control.
I might have a go with the other microsteppers available on ebay, the ones for controlling the laser position in cd/dvd etc drives might have finer control, but then given they all seem to use a screw drive too, I suspect they also have quite a low number of steps/rotation.
B