I have built an add-on, that adds the social like buttons & tweet button to your product pages the add-on does not use the sharethis widget and connects directly to the respective social networking sites, if anyone is interested in this add-on its $20 please PM me.
it adds the following social networking buttons, facebook, google+, twitter, pin it, submit
Is there a disadvantage to using the ShareThis service? I ask because it would seem from your post that you think it's better not to use it.