Went for a test ride with the new mirrors, and they seem OK. The left mirror is ever so slightly warped/curved, not enough to affect vision, but enough that I noticed. The right one is perfect. Don't think I need extenders, but we'll see.
As for buffering, there's still some there but then I am riding a motorcycle so it's never going to be completely smooth and silent. I managed 90mph on the motorway with my visor open so I think it's pretty good.