The type of freight would be open. I'm guessing a lot is automotive going over there & coming back. When I did this in the past most of my freight was auto related.
.75-.85/mile? Yowza. I wouldn't do it for that. You have the bridge tolls, the wait time at the bridge, the extra cost for cell phone usage while in Canada, fuel prices are much higher. While I wouldn't fill up in Canada, depending on how far I went into it I'm going to have to get at least some gas there. Also the 407 tolls, if ya use it. I'm guessing the milage is calculated using that if it's the shortest way. To not use it means you've extended your trip.
When I did this before, I worked for a low paying company. I was ok w/ it because I went from the GTA to Michigan. Then Michigan to the GTA. That was fine. Later on the border agents really started getting to me. Also though, I talked to a driver from another company at the Honda plant. (Maybe Toyota, been awhile since I was there)..
He had taken a run that picked up about 20 miles from where I did. When he told me what he made on his run, vs what I had made, I felt that was too much to be leaving on the table for the sake of being in a Michigan/GTA loop.