Visibility: Magellan Meridian Gold vs. Color

I'm looking for a GPS with mapping capability for my motorcycle. My
first consideration was the Garmin GPS V, but I feel that the lack of
memory expansion is a serious limitation (I don't want to haul a
laptop with me on long trips).

I am intrigued by the Magellan Meridian Gold and Meridian Color. On
some products (e.g. cell phones), I have found that a grayscale
display is much easier to read than a color display when viewing in
bright sunlight. I would appreciate any observations and comparisons
between these models with respect to viewing the display under various
lighting conditions, especially bright sunlight.

Thanks,

Tim