There has to be a point
There has to be a point at which a limited edition steps over the production line and is not truly limited. And there has to be a point to a limited edition. And there has to be a market. WIthout all 3, then it's an ego rash.
I read recently about a Japanese department store that sold a limited edition of 300 Omega Speedmasters. Outside of a white dial, there was nothing that said limited edition or numbered the edition or "marked" the watch as anything special other than a special order. But it was perfect for the market. Japanese watch afficionados (and their international brethren) jumped all over the watch because it was limited even without any identification, but the secondary market has not been kind to these watches.
Some watches are limited to very small numbers because they have significance (Tag/McLaren) or the materials are very difficult to produce (Jaquet Droz Paillonnee) and others have significance in their numbers (Cousteau).
So if IWC were thinking of a limited edition, there would have to be more questions asked before a number could be determined.
I think the opinions expressed by many today constitute the basics of a good marketing discussion.
One of the interesting side notes of the manufacturer who did the limited edition of 200 was that the watches were sold directly from the manufacturer to the collector. Speaking to a couple of dealers, they felt "cut out" of the equation.
However, the buzz that the watch generated was huge in the collector community. Owning one became a badge of honor among collectors, so to speak.
Larry