Well "Outlook (new)" finally stopped OOM-ing on my very normal-sized inbox, so I went back to using it over Outlook Classic... Can't say I notice a difference much these days.
(Not a residential inbox, the "I work in IT" sized inbox with all the email alerts about jobs failing...)
"Classic" was never very stable to begin with, and seems to be getting less stable every monthly patch cycle. Decades-old problems remain unfixed, and "new" Outlook still doesn't have all the features of the old one (or compatibility with in-house programs that use MAPI integration, or COM add-ins). "Classic" must have been such a spaghetti-fied mess that they thought they couldn't actually fix it at all and needed to replace it. But I'm not sure that's really the solution... is it ever?