As a diesel owner for going 4 years,(Ford 6.9 and 300D), I'd urge caution cranking without using the glow plugs.I use mine whenever I have a cold start situation. Posts on the Ford Diesel website mention the possibility of the plugs coking up if this practice is used on the Navistar V8 diesels, making them possibly difficult to remove. Once a plug sticks in the head, if the end should twist off on removal, the head will have to come off!
I can't say that the Benz would do exactly the same, but why risk excess battery/starter wear? The Fords have dual batteries, but our Benzes only have one.
'85 F-250 6.9L