After a long and laborious search, I think I've finally found a pair of shoes that fits- the La Sportiva Wildcat. Only sticking point is the lack of a rock plate, but I'm going to at least give these a try before ruling them out for backpacking. Got them cheap enough at Running Warehouse to keep them for daily use or day hikes if they don't.
To my surprise, I've come out of this being pretty disappointed in New Balance's offerings. I've had many pairs of New Balance in the past, all 10.5/11 4E. They have a reputation for consistent fit for a given last. I'm not sure why, but that hasn't been my experience with the trail runners, all of which seem to be built on the PL-1 last. Street joggers built on the PL-1 last in 10.5/11 4E fit me well, but the PL-1 trail shoes all seem to have significant differences in fit- too long, not wide enough fore or mid, heel is big and sloppy, etc.
Whoever runs Running Warehouse gets a bunch of credit from me. All of the sizing details were really helpful. Shoefitr came in handy as well- doesn't factor in widths correctly, but it was very useful and pretty accurate in comparing relative fit between shoes I had already tried and ones I was considering. Shoefitr's sizing comparison between the NB and Montrails I've tried and the Wildcat were spot on.
Original Thread, which I've kept up to date as I've tried new shoes.