Another route to get to the same place
Another option that is used in the accounting field is not a non compete, but a contract that if the employee leaves and takes your client, they have to pay you a percentage of the fees generated by that client for a set period of time.
If they want to go into business for themselves, fine, take my clients and pay me the revenue you generate for the first 2 years or some period of time.
This seems to be more readily enforceable as you are not restricting the person's ability to go to work where or for who they want to. You are just being compensated for them taking your business.