I wouldn't go without the screen.
At first I was thinking the same, as I really didnt want anything else in the car, wanted the OEM look.
In my local halfords auto shop they had the 9000, 9100 and 9200 on display. I really didn't like the 9000, as everything is done over audio commands. So it reads the menus to you.
With the 9100/9200 you can have this option, but its so much easier just using the jog wheel.
Although the Voice recognition is good, its not perfect. And some names it really struggles with.
The screen has a really great on-screen address book. Its really easy to quickly find the contact you want to call.
No way I would go without now.
It also makes caller ID better. If you have the 9000, it tries to read the names out. (again you can enable this on the 9100) and it sounds bad for some names, and takes too long if the name is long.
Even worse if you dont have the number saved as it reads it out.
If you have the screen you can just see the same and hit red/green.