The 2000 FCW and 2003 FCW have a slightly different, more sturdy shutter mechanism.
So if there is a choice, get one of these FCW models.
Not that the older ones are bad. Far from it.
But with very few people wanting to work on these even when they were still in production (too complicated), anything you can do to ensure that you will not need to find someone who is willing to (and capable of) repair your camera should it ever need it should be done.
Chances are that a broken 2000-series camera will never be revived. Once broken, always broken.
So to minimize the risk, choose a model that is least likely to fail.
More important however is that the shutter curtains are free from imperfections. A slight mark, dent even, will not necessarily make a shutter useless. But it is the beginning of the end.
Metal foil makes a good material for shutter curtains, because you get very thin, very lightweight, opaque curtains with great tensile strength. Something Hasselblad needed for his ideal shutter (as a bird photographer, he needed something as fast as possible).
But while great under tension, i.e. when the curtains accellerate, very thin metal foil is lousy when the curtains need to come to a stop again. It buckles and folds.
The corrugation of the foil gives it some rigidity in one direction, while still allowing it to roll around the rollers on either end.
But there's a limit to wht it can do. With dents caused by uncarefull handling, the chance that the foil will buckle is much increased. Any creases and folds are signs that it already has done so.
So to keep the lethal, final buckle and crumple as far aways as possible, look for a camera with perfect shutter curtains.
The Palpas, internal anti reflection coating, is only in the 2003 FCW, absent in all other, earlier models.
The "M" in FC/M stands for "M"odified. Just as it does in 500 C/M and EL/M, 501 CM, SWC/M. The last one doesn't even have a mirror. So it's not that.