Hi Adam,
New old stock is far less important than total condition, accessory set completeness, and your true depth of interest in the watch.
For example, would this watch still intrigue you as deeply if a fellow collector were offering it used? Do you love the actual watch or the idea of an *unsold * example. As Nicolas observes, that status won't last. Love for the model must come first, because the intangible quality (and any market value, for what that's worth) will evaporate once you wear the watch.
And then you're left with the original question; all else equal, was this the watch you desired on its own enduring merits?
Finally, service is a concern on a decade-old complicated watch that has not been opened since it left Le Sentier. No oil-based lubrication lasts this long, and the watch almost certainly would exhibit very low amplitude on a chronoscope if tested. I had the opportunity to buy a 13 year-old NOS Grande Memovox a while back, pulled it from the box, watched it run 215 degrees of amplitude on the scope (with proper lift angle computed), and I sent it straight back to the factory to have the "new old stock" oil and grease ultrasonically removed.
Ultimately, buy the watch if you would find it equally appealing if purchased pre-owned in excellent condition. If that notion dulls your ardor for the watch, it's probably not the model itself that appeals to you. In this case, it would be best to find the model you favor most, and, in an ideal scenario, enjoy the satisfaction of being the first owner of that watch.
Best,
Tim