> Cuts out a connection and a significant amount of slower subway travel. > >

Transfers take a lot of time too. On the weekends I've seen 20 minutes between Red and Green Line trains. One less transfer could easily save you that much time. Possibly more, if a transfer causes you to miss an hourly bus for example it might cost you an hour or so.

The other cool thing is we could run trains between say Worcester and Lowell, or Lynn and Framingham, or any number of connections that currently are basically "I need to drive or spend 3 hours on a train/subway/train" with the hourly commuter rail trains and occasionally 20 minute headways on the subway being huge "fuck the T, I'll drive" points.

And if we can run trains between North and South station we could probably make due with less trains. Or run trains at higher frequencies. That gives us some good options. Maybe we take a few trains from a lesser used line and put them on those Worcester -> Lowell/Lynn routes I mentioned.