I signed one and worked for a guy for 6 years here in California. He let me go to cut overhead ( he had money trouble and eventually went bankrupt ). I started my own deal instantly and he took me to court and the judge basically laughed at it because it a right to work state. Only time those stand in California is if you are selling a business but they don't hold up for just regular employees.
I agree with Rob Allen. Firstly there is no such thing as a no compete clause, at least in CA. Secondly, if you run a tight ship, high quality and have a following, customers will choose/follow company over an employee. Last, if you have that image, then you must have good employees, so pay them well, treat them well and non issue! Get rid of dead weight as dead weight won't go far. They may know how to clean but have no clue how to run a business.