How Binding Is A Non-compete If An Employer Doesn’t Follow Employment Contract

I've been with the same MD based company for 10 years as a salary employee/manager. They made me sign a non-compete when I was given a raise, along with an attractive quarterly bonus plan for sales/performance. I have met the requirements for the bonus every quarter since but have never been paid out the bonus. Another company has made me a more lucrative offer to basically do the same job, with less responsibility. Should I be concerned about the non-compete since my employer hasn't lived up to the contract? Could they still make accepting another employer's offer a huge headache even if it's non-enforceable?