IWC in New York is offering "at no cost" to give you an estimate? Does that include return shipping with insurance if you decline the service quote? If the watch sets, winds and runs, then there aren't likely to be any broken parts--there may be worn parts however. Setting aside the precautions needed for mailing a vintage gold pocket watch across the U.S. I would not do it for the following reasons:
1) Once IWC has the watch, the will quote you for a vintage restoration, not a standard overhaul. Looking at their prices list for wristwatches (its downloadable), I see that the least expensive is $490 for mechanical movement without complications, and goes all the way up tp $2,490. I would imagine that they will charge you a premium price for the restoration of a 105 year old pocket watch. Your guess is as good as mine on this one!
2) I would get clarification on what the procedures are for declining an overhaul. I don't think they can provide you with an estimate without doing some preliminary disassembly, and it seems unlikely to me that this will NOT incur a cost if you then say "no thanks" to moving forward with service after the quote--and they WILL charge you for sending it back.
J