congrats! I also hated the z4 when it debuted and I never thought I'd own a BMW! I have three in the garage now
and also like you I traded my 997 in for my e85m
I actually love the n52 motor as it weighs less than an s54 by 100lbs! and the motor loves to rev w/ a lot more down low, and it doesn't need valve shimming every 30k mi. If this were my daily purchase I too would have chosen the SI
you really cant go wrong with any BMW I6