The diesel is the lower risk "reliability" option. Sold in their zillions and readily maintained by everyone, even Piotr and Krzysztof who work off their driveway a mile down the road.
The petrol hybrid was sold in tiny numbers for a short period of time and adds all kinds of tech risk, for little performance benefit: speed / economy / whatever....
I looked at, and drove, the S500Lh and found that the only real benefit is silence and ultra low emission on short runs, and maybe a few pennies saved on fuel "if" you can be bothered to plug it in.
If you're doing long runs or big mileages, the diesel is the absolute no brainer. And I say this as someone who loathes "luxury" diesels except in taxis.