I agree with Kevin C 100%. Horizon Blue is a great color, albeit a bit unconventional which makes it a bit desirable, I would think.
Aside from that, however, if you do decide to change the color, follow 2 basic rules to minimize any problems (which you foresee)
1. Paint EVERYTHING the new color that had the old color on it; do a 100% job. If you can tell from overt appearance (w/o looking at the data tag) that the color has changed, this is not a complete job. Dash, door jambs, engine bay, etc. all should be done.
2. Use a Mercedes color that appeared in the model range…not Ford Blue, or GM Yellow, or some made-up color.
You probably will minimize any future complaints when you come to sell by doing it right.