Supposedly the bus gets slightly better NPS from the ever so slightly wider cabin all things equal. I would imagine Econ/Perf numbers are very similar. BOS is a 4 season travel heavy market that punches way above its weight class while sweeping the leg while it’s at it. DL of not that long ago basically paid a billion to indirectly build and gift for free a terminal for a ruthless mega LCC that became the biggest carrier in BOS history and they use the bus for long routes. It took DL decades to claw back to the top, ever so barely, and I doubt they want to give that up by lowering NPS even 0.1 points.

Maybe the MAX “is different this time” and the cabin is as good or better. Or maybe network sees a nickel per flight benefit to it over the bus, in which case it’ll get more routes than the bus.

IMO BOS is a phenomenal market and we need to leverage every possible advantage there to protect our ever so small lead.