Paint schemes have always been a bone of contention with the MBTA. As long as the cars seem to be being used more as Apple Computer billboards, the gray/silver shows up the contrasting ads quite well. The older orange scheme at Mattapan wouldn't do as well on that . On the other hand the Yellow/white scheme on the new buses, which is a descendent of the older (1970s) bus scheme with the blue stripe replacing one black stripe seems to be popular, as do the Orange and Blue Line schemes without the stripes. The Stainless Steel schemes used on various rail cars and the silver line buses are resistant to vandalism, but seem harder to keep clean in general. The Type 7 & 8 scheme with the teal has visibility problems and isn't too popular in this community, where photography is an issue, but makes a great background for those Apple ads! Hmmmm.
As an aside, I know I might get some flack for talking about bus schemes here, but the MBTA has always been one of the most integrated transit systems, and the previously mentioned Cambridge Seven was an attempt to create a system wide scheme.
The important issue is: Are the cars easily recognized by operators of other vehicles on the street and pedestrians? If the answer is "Yes" then the scheme is ok. Otherwise, as Abe Lincoln is reputed to have said, "You can please some of the people..."
The next stop is Washington. Change for Forest Hills Trains on the Winter St. Platform, and Everett Trains on the Summer St. Platform. This is an Ashmont train, change for Braintree at Columbia.