From the "when life gives you lemons" files...
On Saturday 4/23/2022, I returned back to CT from NYC a day earlier than anticipated. After a long night, I was just anxious to get on a train, get home and get some rest. I caught the second train of the day out of GCT and had to wait at New Haven for just over an hour for my SLE connection, but it turned out to be worth it. We departed NHV and headed for State St at a snail's pace, stopping just shy of the platforms. I was in the cab car, so I could see the head end view of M-8s coming into the station, diverging to another track. As soon as they were in the clear and we got the signal, we pulled in. The 4 M-8s passed by us, having "Croton-Harmon" displayed on the side destination panels. I recall asking myself, "what are M-8s doing outside of Metro-North territory". I'd get my question answered shortly.
We operated east on the Shore Line on Track 1, making all local stops except Madison (only has a Track 2 platform - any plans for a Track 1 platform here? Wetlands issues, I'm sure). I got off in Old Saybrook, happy to be back. I hung out in my truck for 5-10 minutes, then heard an unusual (for that part of the Shore Line) horn. I look up, and happen to see those same four M-8s. They pulled in. I walked back to the platform, took some photos, and shot the following video, just as the set was departing back towards New Haven:
Whether this will be an everyday occurrence soon, or just a one-of test, it was a cool catch!