I, for one, have never gotten this Yank 'aboot' thing. Of course, the flip side is that to the Canuck ear, Yanks sound like they're saying abowt.
When I'm in Canada (always Vancouver or Victoria area), I always hear "a boat" for about. I would say that the pernunciation I'm familiar with on my side of the border is "abowt" and wonder what your problem is with that.