So the voice search feature works best with third party apps like Vlingo. I found that using this app with the controller works in the following way.
When the app is installed, press and hold the search key on the remote. There will be a popup on the phone with option of Vlingo and Voice Actions. Choose Vlingo, I set it to be the default for my own preference to take one step away in the future. Then just speak, Vlingo has several preset command words that you use. The microphone audio will be picked up on the Smart Controller not the phone.
The Google Voice Actions application from Google does NOT allow the Bluetooth audio to be used so it will not work.
So try it out works for me
One other thing I found that was helpful for me was that the mouse cursor speed can be adjusted, to do that go into the Bluetooth Settings menu, look for the Motorola RZ100 with the little mouse icon, press and hold this. A popup window will appear with track speed settings, click on that and adjust as needed..
Good luck...