i like decent concaving. it certainly improves pickup (for me). a lot of concaving improves the pickup further but you end up with a bat that feels pretty dead across the face when hitting strokes(once again, for me, maybe not for you). i love the beautiful ping of the middle on a full spine bat, but for me, it feels bottom heavy at times and i feel i need to take 1-2 ounces of deadweight off in order to find the pickup of the medium concaved bat. i certainly don't mind a smaller, full spine bat, but i just feel more confident wielding a bigger piece of willow.