My 2008 S was rear ended last week. Damage was limited to the suspension on the left rear which was damaged enough to bend the wheel a few inches forward and down. The insurance company is replacing all suspension components on that side including the wheel bearing, carrier, tire, wheel and shock (Bumper and tail light will also be replaced). The tires are brand new so I'm not worried about only one new tire but the shocks have 190,000 KMs (120,000 miles).

Would that not be dangerous as the new side would have different characteristics vs the old?

 

I would not recommend replacing 1 shock, especially on a high mileage car where the shocks are likely to be well worn. I may not be dangerous, but it will likely affect handling negatively.

Replace both shocks. I would not trust any reputable repair shop that only replaced a single shock on a high mileage car. They should be telling you that both shocks should be replaced.