I agree with Gilly.
Bosch is marketing their Plats to the point that we are having to run all over the place just to find Super/Copper. And we all know how some Benz Hate Plats !!
My thoughts on Resistor plugs for Benz with Distributorless Ignitions [ and I notice KYB is also recommending Resistor], is
that because each coil fires 2 plugs at the same time, you are now taxing the coil because the resistance is double. KYB's info page claims this is insignificant, but does not mention 2 plug firing.
[Also something to remember for those who like to open the gap past spec. Total gap is double for one coil]
So I stay with the copper and have been satisfied. [ and they cost less- which is not my motive].
Benz claims [ and I agree ] that the plug firing on the exhaust
stroke requires less power from the coil [ no load] in the "Waste Spark" type ignition. But I think adding additional un-neccessary resistance that has to be asorbed regardless of which stroke the engine is on is not for me......

I might go along with using a resistor plug and get rid of the resistor /boots that seem to give so much trouble , but doubleing up on the resistance does not make any sense except to the Marketeers ..