Does IS help with slow moving subjects?

I was shooting a musician standing still, on stage, singing and playing guitar.

How would you categorise that subject in terms of movement? Overall, the body remains fairly static, and apart from occasional changes of stance, the guitar doesn't move much.

But the face, not just the mouth, but the entire head can move around quite a lot, and this may often be the case with any non-posed subject, there will be movement.

I was shooting from some distance, and the stabilisation enabled me to get a good shot of the static aspects of the subject, so in that sense, it was better than not having stabilisation. In a theoretical scenario, one might use a tripod, but in real-world situations that isn't always practical.

But to continue, I checked a few of my shots. Every single one suffered unacceptable motion blur from the subject. So I just kept on shooting. I took about 80 or so shots and got one good one. Purely by chance I caught the subject at a pause in the motion - there were a few such pauses - but this one happened to be photogenic too.

I'm just glad I wasn't shooting with an SLR where the clattering of the mirror and shutter would have had me ejected from the premises for causing a disturbance.

Regards,
Peter