I'm all for the added redundancy that a Diesel loco would provide to trains running under the wire here on the NEC. This time of year is especially bad when trees pull the wire down and your tin cans Amfleets are struggling to retain their heat. I remember #66 that was dead on the Hell Gate for 5+ hours with no overhead power in freezing temps. Lets say there's something fouling tracks ahead... At the very least you still have HVAC, lights, WiFi, working bathrooms while you wait for track. And if **** has really hit the fan ahead, you change ends and head back to the nearest station. I personally don't care how much dead weight the diesels are to tote around under wire, at least it's there when you need it. Redundancy is everything.
The Acela I's redundant power cars have proven to be a saving grace. I think passengers would be surprised to know how often that second power car prevents dead-in-the-water trains/train-to-train rescues. Not even knowing they've been running with a power car offline. And that's the point.
I also like the somewhat distributed-traction from the Charger and APV, which might possibly assist with seasonal wheelslip delays.
Also, it could cut down on terminal departure delays since looping the trainset can resolve ACSES failures fairly quickly. Another common occurrence on the Acelas.
Since the ordering of the new Viewliner II, I had been hopefully that Amtrak would expand checked-baggage service in the NEC, providing for checked baggage not only on 65/66/67, but also on LD connecting NERs such as 95, 171, 174, 178 for example. The company wants to improve entrain/detrain, onboard and in-station safety and reducing the amount of carry-on baggage would absolutely help that. So many passenger injuries happen when people are struggling with bags, steps, gaps, slick vestibules, escalators, etc. Providing realistic, convenient options for checked baggage (NOT check your bag the day before you travel...) would absolutely help that. It's clear that this will not be a reality with the new equipment, which is a shame.