Im very confused by why some folks think that NJT can't or won't assign particular equipment for particular runs....they do ALL the time.
Multilevels on Trenton locals? Why would you put a piece of equipment that inherently can't get out of it's own way on a run that demands high performance? And please, save me the 'bububut the ALP-46As!!!' talk. An 8 or 10 car multilevel train's a dog, period. Maybe if NJT followed best practice elsewhere and put 2 motors per 8 cars*, you'd get somewhere, but with one ALP and 8 multilevels, they just don't accelerate. And who cares what the top speed is if you seldom hit it and stay there.
If you want to see acceptable performance for a train in this day and age, look at the newer MUs overseas, BART, or:
See, NJT can do it too!
Hell, if they could just get to Arrow levels, it'd be a help...
The only line where it doesn't really matter what kind of train it is a NY to Trenton train
Which has gotten significantly slower over the years as NJT's moved onto slower and slower equipment.
or a train from Hoboken to Dover, which can be ALP or diesel push pull, or MU.
Why the hell would NJT run a diesel to Dover, other than as a positioning move or lack of electric equipment?
Back on topic, Can NJT get a multilevel EMU that's worth it over push pulls? Maybe. I don't see them hitting RER or S Bahn Zurich levels though (Both are on par with the Arrows, which is an accomplishment for the amount of space the actual propulsion system has**), unless they're willing to toss the existing multilevel design and go for something lighter (if that's even possible, which it might not be, though I don't think Snowmobiles, Inc can optimize a design
as well as the others can, though the coffin cars are actually pretty decent, but that wasn't a Snowmobiles, Inc design). With an aluminum body and some modern design and some compromises, they could get far better than pushpull performance, though...
*As seen on other push pull systems in the world, notably Zurich, where the stations are farther apart AND the top speed is MUCH lower. And I'm pretty sure the S Bahn's motors are a few hundred HP more powerful, to boot.
** The transformers are above the trucks in the passenger space, along with the converters, the inverters are in a cabinet behind the cabs. It's VERY tight packaging, and only works because motor cars = ~125,000lbs, trailers = ~100,000lbs. Amtrak's 25hz system should help a little bit, though, over Zurich's 16hz system.