This is very much personal issue, do you want the latest things and are you willing to pay for it, or not.
I had the same situation when looking for X also. I drove 4.8is also and I have to admit that engine is better having more torque in low rpm and I also like the 6 speed automatic. But that's about it, for me anyway, so I considered that paying $15-20k more for 4.8is is not worth it.