I went with the Blaupunkt Bremen for my 911. It looks much like the period units delivered in 911s. The are that looks like a cassette slot is just a door that hides the USB port to charge the phone, or use the phone for music or navigation. It also has a micro SC card slot. Bluetooth, and it all works great.
I have had it for several years, and many long trips, and 10s of thousands of miles and it has been flawless. The big rocker switch on the right side is to skip to the next song if it is playing a song I don't care to hear. I have a 16 GB USB thumb drive plugged into the back with 140 of my CDs on it. Put it on random, and I never know if the Moody Blues or AC/DC is up next.
That Continental unit looks nice as well.