Right now, the Pere Marquette is scheduled to take approx 3 hours CHI-Holland and 4 hours CHI-Grand Rapids.
Midwest Regional Rail Initiative schedules (via Kalamazoo) estimated travel times of about 3:00-3:20 CHI-Holland and 2:30-2:50 CHI-Grand Rapids, depending on how many stops are made between CHI and Kalamazoo.
So, with a Kalamazoo route and South of the Lake improvements, Bangor and St. Joseph lose service, Holland sees similar travel times as now, and Grand Rapids sees faster times.
I'm not arguing in favor or against such a reroute, just pointing out what the studies in the last couple decades had been looking at. Obviously if we're just talking about the single daily train, it's a different situation than a full MWRRI build-out.