The weekend Niagara train runs in service for 9 hours per day, similar to other trains in the network. It's a single trainset which does two daily round trips with a one-way travel time just over two hours.
And besides, a train with 2 F59s has more power than an MP40 (6400 hp vs 4000 hp) and more traction (8 powered axles vs 4). So it will definitely accelerate faster. The only downside is that there's a lower top speed (134 km/h vs 150 km/h). So you'd think that they'd put the F59 sets on a run which doesn't reach 134 km/h anyway, which is nearly every other run in the network.