Not NY to MIA, but on Sunset Limited from New Orleans to Los Angeles: in spite of the ridiculous arrival time at LAX, we arrived even earlier! While surprised, I did not complain. Glad to know that Amtrak can be on time or even early sometimes.
I have traveled from NYP to ORL many times and have never been late more than a few hours. In one instance, there was a police shooting near the tracks south of JAX, and both Silvers were held in JAX for a while. Consequently we were delayed by the shooting, then delayed because we were following the Silver Star and then delayed because we were "off schedule" and had to defer to SunRail. However, I think I may have been early almost as many times as I have been late.
I have seen longer delays when I was not aboard, but I think it is an extreme exaggeration to state that the train is always late.
I admit I'm always mystified and amused by conversations like this where statistics exist and no one has to argue or speculate. Here for example is a statement in an article dated April 28, 2016 about Amtrak's on time performance:
"All is not fine and dandy across the board, however. Two examples are the Crescent (New Orleans to New York City), which is late a little more than half the time, and the Silver Meteor and the Silver Star (Miami-New York City). Together, only 49% of their trips manage to arrive on time." http://www.trainsandtravel.com/2016/04/28/amtraks-otp-is-mostly-aok/
I'm sure this is based on some published statistics the author found.
I suppose if one digs down into the published statistics we'd know about the duration of the delays and perhaps the causes. But I'm not sure why people speculate about these things when there are statistics.
The Silvers are indeed late often enough, that I always make contingency plans for it being like 1 hour late, 2 hours, and 3 hours. I will admit, I never made contingency plans for it being early, and sure enough, we were over an hour early once. Though, being a Sleeper Class passenger, we simply went up to the ClubAcela and killed that hour in there with some snacks and soft drinks.
Only time I was ever late was on the Missouri River Runner. We got stuck behind broken freight train that could only go 2 m ph and no siding big enough to pull over. Finally it quit to running all together and they sent a bus to bring us into Kansas City 4 hours late.