The advantages include maximum freedom, you are not limited to only HMO network providers, and co-payments are low. Disadvantages include that co-payments for non-network care are high and general referrals for specialists may be difficult. With the recent passage of the Health Reform Act, POS plans may be changing considerably. In the past, it was necessary to have a referral from your primary care doctor in order to see a specialist. POS stands for Point of Service.