Lower CG is always good, the suspension has to be tuned to the new requirements or else you end up worse if you don't now what you doing (yokomo bd7'16 anyone?)
Xray is between a rock and a hard place. If they go extra low shocks and praising the lower CG what stops me to go full lower CG and get an Awesomatix? If not they have to avoid getting a stale design, because Xray is always going forward, so what do they change? This is where mugen can and should praise it's design choices and put other manufacturers in check, the arm provides far better wheel alignment control, durability, etc...