Owned a '09 Z for almost 4 years and have had a Estoril Blue M235xi for almost a month. It is fantastic! I was trying to find something that was a combination of fast and fun like the Z, but with back seats, quiet, comfortable, AWD daily driver like my old '13 Chrysler 300S AWD. And the M235xi has delivered in spades. True the Z has more direct steering with more feel, but the BMW makes up for that by being more agile, better balanced, just more "cohesive". You want to just throw it around. And the power...just hauls a$$ from almost off idle.
Now the Z has some emotional appeal over the BMW: loved the sound of my Berk CBE, loved sitting in the cockpit, and it just is a fantastic looking car. But when you combine the driver dynamics with the livability of the BMW - I'm very satisfied. Really sucks to sell my Z, but I sold it to a friend I work with so I still get to see it all the time
BTW, yes even with xdrive order the summer tires (no cost option) so you get the slightly wider rear wheel and top speed limiter set higher. Get some good all seasons for winter and leave the PSS for summer duties.
Sometime in May me and my buddy are taking both cars to the track to compare them side by side. Hopefully we'll get some good video we can post here.