I haven't ridden at Barnwell Mountain, so I can't speak first hand. However, lots of my regular riding buddies have ridden there a fair bit, so I can say that there's plenty of tight trails through the woods, lots of rocks, plenty of nasty uphills and downhills on loose rocks, and if it's been raining, plenty of mud. In other words, it has just about everything except desert. In any event, do not expect much flat, wide open riding. Many people assume that about Texas, and you can find lots of that land, but not on the enduro circuit.
I mostly like the West Texas events, because I prefer dry and rocky to muddy and trees.