I would have voted for Neal, as a centrist. But the accusations against Morse now strike me as totally bogus, ginned up by College Dems who were acting in bad faith. That's not good for actual victims of inappropriate sexual behavior.
Massachusetts has had two successful House primary challenges in the last decade (Moulton and Pressley)
You're right that I wasn't thinking about the Pressley/Capuano race a couple years ago, which is amazing since I was following that race and had family vote in it.
But there are some instructive differences, as Pressley had national left wing support, and a fair amount of local establishment support from Maura Healey, various newspapers, and other Massachusetts politicians.