Our strategy has been significantly limited by DD's weakest skill set-- her writing.
While not a "2e" issue, exactly, it's been a problem for her because she is functionally PG in every other domain, but as geofizz notes, when you're considering acceleration that is way radical (+3 years or more past agemates) then you also need to consider whether or not the ancillary demands can be met.
In writing, there is no real way that my then-9-yo could have functioned in a non-majors physics course at the collegiate level. The material would have been roughly right (she'd have been at about the 80th percentile in the class cohort, say), but the writing expectations were so much beyond her that there was little hope of making it work. I say that even in light of aeh's anecdote; I doubt very seriously that my DD would have managed even exams given her writing deficits relative to the demands.
Those gaps are a real beast to work around; you sort of have to manage it like a 2e issue that you get no real support or understanding for, to tell the truth.
It's unfortunate, but it means acceleration to the point that the weakest skill set can be made to TOLERATE, and then afterschooling/supplementing to accommodate the need for more depth/rigor/challenge in the placement.
