Let me address this Phase IIIb nonsense.. There is no such thing.. It's phase III with a reflective strip that was a different color when Phase III was originally out. Nothing is different about it.. STOP calling it Phase IIIb!!!!
Actually it's a little bit more then that.
The Red & Blue stripes are a different shade of their respective colors (the originals were a paler shade), The Reflective stripe as you mentioned is different (original was very inconsistent, I know of 3 different styles), and the whole striping is narrower. Then we come to the logo. The original III didn't have the Chevron on it really at all, the new Chevron logo, now has a white outline, uses Frutiger as the font (rather then Helvetica), the text is blue, and it's on the train cars now.
So Phase IIIb makes a lot of sense, especially after looking at the changes from Phase IV to IVb.
As a designer, this whole 'Amtrak America' thing reeks of design by committee. For one the logo it's self looks like someones secretary did it in Paint, The notion that certain cars will get III while others stay in IVb, even the idea to use an 'old' design. I feel like they went with "John's secretary did a nice logo, lets use that. Oh and Sue want to keep some cars in the current paint scheme. Do you have any request Bill? Sure we can use an old paint scheme. Karen do you have a preference as to which one?"
Instead they should have just hired a design firm (like they did for the Acela) and said "To go with the arrival of some new equpment we'd like to roll out 'Amtrak America' branding on our long distance fleet. Can you make us a brand for that?"
On a related note, I've started a personal project updating the Phase IVb paint scheme, calling it Phase VI. It's still a work in progress but here is how it's coming:
https://drive.google.com/open?id=0BwoszLS0nWxPSWpOa283UDh6NjQ&authuser=0
peter