When I put the 617 turbo engine in my '85 300D (which being a Euro, originally had the non-turbo engine), I discovered I could no longer fit the engine shocks. When driving the car, there is no difference, as far as I can tell. The difference comes at idle, where the engine rocks gently without the shocks. It's nothing harsh or dramatic, but it is noticeable and isn't very Mercedes-like. And as mentioned above, you probably feel the engine shudder a bit more at shutdown. But again, not a big deal.

Incidentally, the diesel G-class of the day had the same engine, but didn't use engine shocks. The motor mounts were beefier to help compensate, but some vibration is still present. Refinement was obviously less of a priority in that vehicle back then.

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1995 E300 200k
1981 300GD unknown km