I got my Roccat Kone + quite recently.
Other differences between the Kone and Kone + are:
1) The Easyshift option which allows you to assign a second function to each mouse button when you hold down the Easyshift button.
2) The Kone + has more patterns and options for the LED lights
3) Looks slightly different (better imo)
Apart from the sensor, there aren't any other differences I could find. To be honest, I wouldn't say any of those are worth the extra money. I never use the Easyshift function and the other two are just aesthetic. Would probably save my money and go for the standard Kone if I could do it again.