If you want your car to look that way, and if you're planning to hold onto it a while, then do it - because you needn't worry about the market value.
But before you do, find an NSX-T in your color, to see what yours is going to look like. You may very well decide that it looks better with the black top, even though you might not feel that way now.
When I first got my car, I thought I would have preferred the "monochrome" look - until I actually saw one. Then I realized how well the "disappearance" of the contrasting black roof set off the gorgeous lines of the NSX bodywork.