Responding to your points:
From a text book point of view it wouldn't make economic sense to use other companies to move a product from Point A to Point B because we all know that the more railroads you add into the equation the smaller cut the railroad would get.
I think you are confusing line-haul "alphabet" routes with the haulage agreement idea that I mentioned. I ask this respectfully: do you the understand haulage agreement concept? Under haulage, the contracted carriers (in this case PAR and SLR) typically charge a per-car or per car-mile fee, regardless of commodity or "retail" revenue. In addition, those carriers are not responsible for car-hire. As such, the pricing is normally very reasonable. A New England example of this was the agreement established in the late 80s (?) between GRS and Conrail to divert interchange traffic from Rotterdam Jct to Barber Station, MA. CR charged a flat rate of $75/car, I believe.
Regarding train counts, I stated my numbers on an "each way" basis. I'm not up on actual train counts, but it looks like you're mixing TOTAL and EACH WAY. Again, my daily estimate is 5 EACH WAY, or 10 TOTAL, give or take. If I'm off by a couple, so be it: my statement of underutilization still stands.
Regarding routes, a couple of points: If the old CP line is so strategically superior to the CN line, why has the CN not taken a more active stance in trying to control that line? Also, "truest?" The difference in mileage between Maine and, say, Chicago is minimal comparing the US route vs routing 'over the top." By the way, keep in mind that when you are supporting an "over-the-top" routing, you are exporting transportation jobs and services to Canada. Not saying that's wrong, but a lot of people would.(Btw, 130-car trains are not dangerously long)
And what the heck does Halifax - New York container traffic have to do with the line west of Brownville Jct??? Regarding ports, shippers DON"T HAVE AN OPTION about ports. They use the ports the steamship companies call on. And given the continuing trend of larger and larger container ships, port selection is going to DECREASE over time, not increase. I recommend you read "The Box" by Marc Levinson. It gives great perspective on why port locations have evolved as such since the dawn of containerization in the 50s.