Once again: do not compare E53 4.8is with E70 4.8i. It's like comparing regular 3er coupe with M3. Or 320i with special edition 320si. Very different personalities.

E70 4.8i is a substitute for E53 4.4i, NOT 4.8is - despite same 4.8 designation.

A performance version of E70 will come later - just like E53 performance version came later after E53's launch.

Btw, E70 is a very capable vehicle - definitely much better than E53 (comparing entry I6 & V8 versions).