No the 560SEL's transmission is less dependent on vacuum controls than the diesel transmissions, however it is just less dependent and thus still has some vacuum issues that he should have his mechanic check out. My 300SD currently has a very bad, jerky, abrupt shift from 1 to 2 and from 2 to 3 and that's one of the things I need to attend to as I know it is vacuum related.

__________________
1999 Mercedes-Benz S600, 103K miles - garage queen
1988 Mercedes-Benz 560SEL, 89K miles - daily driver
2007 Hyundai Sonata Limited, 31K - daily driver