Stator / regulator replacement on both of my bikes earlier this year probably took me about 6 hours each, and I am *not* a motorcycle (or mechanical) technician. A ton of time was spent just getting one of the screws holding down the old timing coil off, as it seemed to have seized.
Draining the oil and antifreeze is part and parcel of replacing the stator. In any event, the stator doesn't need to be replaced unless the battery isn't charging - this results in the scooter NOT STARTING, not in it cutting out. If the bike is not charging, you will see the display go wacky many many miles before the bike actually dies, and you will not be able to restart it. (Actually, you won't be able to restart it long before the instrument cluster goes wacky, but I digress.)
It sounds like the mechanic isn't sure what is wrong and is replacing the parts shotgun.
I will also reiterate that I am of the opinion, that the Xciting 500 IS NOT RELIABLE ENOUGH TO BE A SOLE MEANS OF TRANSPORTATION. Kymco kind of screwed the pooch on that motor. If you are in bad financial straits, I recommend selling the bike and getting one of their 250cc or 300cc models, which can also do highway travel, and have suitably reliable drivetrains to be a primary vehicle.