It's just selling a property at the end of the day, so it comes down to supply and demand. You'll find that the people who sold it to you will have little interest in reselling yours becuase they probably get paid up to and sometime more than double the normal sales commission.
You'll find that investors will be happier buying, however if there is a display suite, then people looking for PPOR may nibble a bit.
Word of warning, if you're thinking of selling an off the plan property and you're getting close to settlement, either be prepared to lower your price or have finance ready to buy the thing - last think you want is to be hanging onto a property you don't want, can't afford and can't sell.