It really depends on what you want to do with your career... a masters degree is beneficial if you are seeking a position as a lead security architect or engineer, manager, or want to work for a security vendor as a consultant or sales engineer. It looks good on paper and can improve your initial salary prospects by $5k to $15k, depending on the employer.

That increase in salary becomes a higher base for COLA increases, bonuses, and starting salary if you change employers.

I would find an employer that pays for your continuing education, as well. Many larger employers will provide tuition assistance or full reimbursement for your degree. Have them pay for it if that is an option.