L'DOR VADOR HU KAYAM...
Daven Well, Don't Talk, and Sing Along!
The preceding copyright (c) Lincoln Square Synagogue and Sherwood Goffin
Well. That clears up something I've long suspected. Listening to people lead davening, those who say aloud "Ledor vador ... la'ad kayamet" seem to be people who learned to daven Before Artscroll, while those who say "Al Avoteinu..." were those who learned from Artscroll. This confirms it - the Chaz says outright it is an error in the English Artscroll.
Contra the Chaz, I wonder if it's a Nusach Sfard thing. In the all-Hebrew Nusach Sfard Artscroll, at least the chazan-sized one that I've been using for the past 6 months by the `amud in a local shtibl, I think they do begin at Al Avoseinu.
I checked - yes, the Artscroll NS siddur has the chazan start at Al Avoseinu. Further, I checked with the gabbai, who, like me, grew up Before Artscroll, and asked what he grew up with. As far as he knows, he always started from Al Avoseinu. So now we know - rather than being an error of the siddur printers, it was a Nusach Sfard custom, that leaked into the Artscroll Nusach Ashkenaz, probably because whoever edited that section grew up with Nusach Sfard. Not that siddur printers are innocent of introducing changes in the davening.