I just ran NY-4 through New Britain behind DEY-5 #0615.
This is one of the scheduled trains, with the correct locomotive, at least until I get a better detailed S-2 than the Atlas one. I started with a 15 car train, but it was just a bit too much for it on the helix. I have the decoder set to a maximum of 30 smph (the prototype's top speed). Of course, with a full train it was slower, particularly up the helix. But the prototype would be as well. So I'm not sure if I'll bump it up a bit or leave it.
In the end, it hauled a 12 car train up, with only one location on the helix where I had to give it a push. I'll have to test that point on the helix (last turn before the Berlin Line branches off).
It came up the Berlin Line as appropriate, and I was even able to stop it before the turnout for the crew to throw the switch. There was no problem restarting on the curved grade. It then proceeded and dropped off 5 cars before continuing west to Plainville.
I'll have to remember to bring a camera next time...