At least my reasons why I tell others to avoid hairless rats is simply because they require more maintenance. The lack of fur requires a different diet, they burn more calories than a furred rat just staying a normal temp.

Also, the lack of fur makes them very susceptable to scratches, eye and ear infections.

Another down side to hairless is the females very often to don't lacatate, that is, produce milk. And if they do lactate, it can be very little.

Production and health care wise, it's not a good investment to bring the hairless gene into a colony.