I think I pretty much agree.
Although I'll do oil changes, check fluids, etc., the major service interval stuff I'll leave to the dealer. I like your reasoning about "peace of mind." Reading forums, etc., I've already come to conclusion that taking a Sprinter to a non-MB service shop is risky business.
But on oil changes, I've had some bad experiences with dealers - often overfill, and on one occasion years ago I checked oil after a dealer service and found dirty oil on dipstick - they hadn't changed it even though they charged me royally for it!!
My brother had a Cadillac dealer fail to tighten down filter properly and leaked oil until engine froze up.