Robbie,
While I'm not Ziggy, I can say that neglected movements that exhibit excessive wear and requiring replacement parts may be difficult to service due to parts supply drying up; this would especially be the case on the older movement like the 15xx calibers that are essentially at the end of life for support and parts production.
While there are still NOS parts available on the secondary market, the supply of those parts is finite, or the mark up on those items may extend beyond reason due to supply and demand. Add to the fact that Rolex has tightened up their parts distribution network, and I can see where Rob may be coming from (though this is only conjecture on my part). There will likely be aftermarket support to fill that gap, but who knows about quality?
Anyways... Just my thoughts on the matter. Rob may have a differernt view or thoughts on the subject