My Seller recently asked - Is my Home Listed on Zillow?
In Denver the Company Broker has the option on the listings whether or not to post to Zillow, Realtor.com, Homes.com and The Denver Post when entering a listing.
My thoughts on this is, why not allow access on all these sites. If you don't all listings will show up on other IDX sites anyway. There was a time the Denver MLS restricted syndicating listings to Zillow as they refused to sign an agreement to take down properties off their site after a home goes under contract or closes. The Denver MLS wanted them to be report the correct status. It took them a year to sign the agreement.
So, my answer is - of course, your listing is everywhere I can think of putting it! I hope to get the most exposure I can for your home!