I would only hire someone like me who worked their whole life to support themselves. A JW who is a responsible member of the workforce generally isn't any worse than anybody else. If you get the other kind, however, there can be big problems.
Let me explain: if you get a super-zealous, irresponsible JW who is the type not really dedicated to the workforce and who doesn't care if they get fired or not (because they REALLY don't want to work), there may be a problem for an employer. This type of JW will break a confidence in a heartbeat and reveal things to the elders in the religion (because they think that being a good little tattle-tale is pleasing Jehovah ooops - I mean the organization). This can cause an employer to be sued. These types of JWs have no sense of responsibility to a secular employer because their loyalty is to the religion. This cannot be underestimated and is not an exaggeration.
They are mindless and heedless of any trouble they cause for an employer and will start World War III. Like a person who causes a traffic accident for others and who escapes unharmed, they will leave a disaster in their wake and it will not concern them in the least.
[However, this doesn't address what may happen if a person becomes a JW AFTER they start working somewhere. Hopefully, they won't check their brains at the door and they will continue to be responsible.]