The 7100i can have voice control but you have to install a program called Mobile Voice Control. You can find it at
Welcome to NuanceVoiceControl
In addition to using a bluetooth headset you can also sync the 7100i to your computer using bluetooth instead of the cable. You would have to have bluetooth on your computer.
I've used the DC with the headset. Yes you have to press the DC button on the phone but at least people won't be hearing your whole conversation. The sound quality might be a little better too. I have a Plantronics 510 Voyager. It works great.