I went with aspherical on both sides and absolutely love the added visibility. This all but eradicates blind spots and is absolutely a benefit from a safety standpoint. It will take a few days for you to adjust to it, but it really is great.
+1. I went with asphericals on both sides. This also gets rid of the stupid nanny warning on the passenger side mirror. I'll never go back.
Basically it breaks down like this:
The term "Aspherical" when applied to these mirrors means that the main area is CONVEX, like the NAR passenger's side mirror. Then AFTER the dotted line, it becomes aspherical, meaning progressively sharper curvature as it approaches the outer edge of the glass.
So, if you swap out the passenger's convex mirror for an aspherical, you're retaining the same view as with your convex mirror BEFORE the dotted line, but adding a superior blind spot view AFTER the dotted line. The only difference is AFTER the dotted line.
Swapping out the driver's mirror is a much more dramatic effect: you are replacing a totally planar mirror with a convex mirror in the space before the dotted line, and also adding the progressive curvature after the dotted line. So the view out of the driver's mirror will be drastically different because you are changing the way you see through ALL of the mirror.
It took me a couple of weeks to get totally used to the new view, but now that I'm used to it it would seem crudely inadequate to go back to stock.