IMHO,
Owning one vs driving one are 2 different things.
If the OP intends to drive the NSX-R, or do any kind of mods on the car, the car's value will likely depreciate regardless of the history or uniquiness of the car.
If it is stored "maybe" it will retain it's value.
In the end the original Honda NSX-R prototype that was shown in Tokyo is probably worth more than the NSX-R that is in the UK, so it's all relative
It's all about Hype, and what a collector would be willing to pay for the car..