If your brokerage has opted out of IDX, not to worry. It will not affect the amount of listings that are available to be visible on your site. The only difference is website visitors will need to register in order to see listings.
Below is the response from the TREB Technical Department
"The VOW feed requires you have all the VOW data behind a password protected section of your website where you register each and every user (confirm registration by email) before allowing them access to the data. VOW has about 95% of the listings on TorontoMLS, while IDX has about 75% of the listings on TorontoMLS however they can be visible to users right away. DLA is only the Brokerage’s listings."