Seriously, ST, I find the front and rear head rests more of a problem than any loss of visibility from the external mirrors on the SG. I know they have to be that size to properly protect against whiplash injury (reactive headrests are a great idea ... :biggrin
, but they do obstruct one's rear vision when reversing. I have got used to it, but am always aware of this as a problem.
Our SH is a different story altogether. Not only are the mirrors (and head rests ... ) ridiculously large, both D/S and P/S mirrors are convex. Fantastic rear vision, with zero blind spots; but lousy ability to judge the distance of cars behind me.
Our SG has a plano mirror on the D/S, and slightly convex on the P/S; less than the D/S mirror on the SH though.
I always have the mirrors on both cars adjusted so that I can see part of the rear of my car, so that I can better judge the distance to those behind me.
As I mentioned before, I have very different driving positions for city and country. I find that this helps with e.g. traffic islands etc.