Mark,
if the price will be fair I think it's a good move.
I always thought it's poorly reliable to receive an extract without any inspection of the watch, not mentioning the bareness of information of some extracts sent to me by other maisons.
Once I even called to complain (this watch of mine, wasn't an IWC) the (probably, marketing guy) didn't even understand what I was talking about :)
What's important is the examination to be made severely and by expert people, in depth, so the extract will report the most possible information about the watch.
Wise move for IWC.
To simply know the match between case and movement would be useful to have someone in charge to reply to a mail, like Longines does for instance. That would be the first step for a collector to understand what's in his hands and, if it's the case, decide to proceed further, asking for an extract.
That combination would be the best effort a maison could provide to collectors - imo.