Stop-Start - is it worth it?

[Crazy Dazz]

So my daughter's car has the stop-start feature.
It's never driven in huge traffic-jams, so I suppose it is most effective at traffic lights, but even then I'm not sure how much its saving, if anything.

What concerns me is the fundamental gut feeling that this is stressing a lot of components.
This is not a hybrid, it's a TD with a starter-motor.

The petrol version uses the special stop-start oil 0W-20, but I think this uses a fairly normal 5W-30 Diesel Oil. They seemed to be aimed at providing quick protection at start, but I wonder if it isn't sacrificing protection at the top end?

We've driven it long enough to get an idea of the fuel economy, so I'm thinking of switching off the feature for a while and see if it makes a huge difference.
Given diesel run very lean at idle, I doubt it will.