I've known several photographers who have lost 25k, 100k+ followings by being banned from instagram for posts that did not break the ToS. This has been devastating to their careers as freelance artists. I wouldn't recommend leaving a more tolerant platform (tumblr) to put all your eggs in a FB owned basket. With instagram, it all seems to depend on who the mod is who got assigned the reported photo to look at. Many of these artists now run a backup instagram and promote it on their primary account about once every 2 weeks to keep a solid follower count on it in case their main gets the hammer.