I think it is a cool idea for brandibility sake and is not necessarily a reg fee domain. That said this is not a get rich domain. However if you considering opening a restaurant or hospitality service, know of someone who is or can find a business on Google with the name "4 PM" you have an opportunity for a sale. If it is a new registration I would hang on and try some marketing. If it is going to need renewal soon I would not be so excited to keep it for another year. If you can find that particular client or build a small business off of it it can be a $xxx domain.