Hi Kev
The difference with the flat mirror you get a true vison of any vehicle overtaking you, with the convex ,the angle is wider giving you greater vision but the image in the mirror is smaller. I use a plain(flat) mirror on the passanger side and a convex on the drivers side thus getting a larger angle of view and also rely on the drivers side vehicle mirror to get a true view of distance as my Milenco mirrors are the clamp on type.The other thing I like about the Milenco mirror other than the quality is when I have the mirrors mounted they are at the same parallel distance to the vehicle mirror which means when I power the mirrors to fold inwards to avoid them getting knocked when at port they remain in the same position ready for use when folded out.A minor thing but somthing I like
Von Ryan