Great compilation, Just a reminder the V12 or M120 engine in the early 90's through 2001 had 4 valves per cylinder = 48 valves. This engine was so rock solid that it was adopted and used in the Lengendary Pagani Zonda!
You have forgotten 280 inline six double over head cam (193bhp) this is so overlooked but for uk it a great engine as you do not need these big engibe for our crowded roads, i personally think straight six is smother than v6 The roof control box need to be kept dry, the sillica pouches are very useful. Oil changes every 3000 is not need the whole point of full synthetic oil the long life. As for the wire harness after 1995 they mercedes replaced (the bio degradable) wiring lume with a more robust one The striaght six engine also did not have the biodegradable wiring lumes fitted. Main in europe where replaced under warranty due to it being a manufacturing defect.
The wiring harness will fall apart and with some models (SL600) you can't buy a replacement from MB, you have to track down someone who can make one. Why I've given a pass on an SL600 from 1992 to 1996.