Agree with mumkin. While under warranty finding a Mercedes dealer and one that can even service a B is not something we wanted to be concerned about. Also didn't want to have to carry the fuel additive either. We did not consider a Sprinter this time. We all have to make the choice that best suits our needs and travel style.
After warranty you can have service done anywhere not just at a Mercedes dealership. We traveled with friends for a month last September and the type of fuel recommended by Mercedes for his motorhome was not available in MN. We drove across the line into another state for him to fill up before continuing our travels in MN.
We had a LTV Sprinter for 11 years but things were different then. As I said everyone has the choice to purchase what suits their personal preference. No right or wrong with whatever you choose.