By 30 pretty much everything in Warrens is green and won't attack if camo drops. The couple of mobs that are LB at that point are easy to avoid and/or you can always stop and re-invis if it drops as long as you are semi-paying attention.
My issue with Stonebrunt in the 30s is I haven't really found a place with enough density of mobs, particularly animals. Since it's such a huge zone I found myself running around so much it became annoying.
It's a cool zone though, especially for a druid/ranger. Unique loot (cool looking weapons, bamboo armor etc.) with some decent quests you can try for. Way better opportunities for cash/drops than say OT in a similar level range. Also, no ruined pelts, so bring your spiderling silks and make some padding while you level up.
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Should've made that zone half the size and it'd be a great alternative to OT.