Does the gripper tag still work in Gazebo 7?

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I'm trying to use the old hacky way for gripping in Gazebo 7/ROS Kinetic, as described in this thread.

I've had no success with the object attaching to the gripper. Is gazebo still supposed to attach the object to the gripper?

I've got a dual gripper configuration - the surface properties are as follows:

<gazebo reference="${name}_link">
  <mu1>1.0</mu1>
  <mu2>1.0</mu2>
  <minDepth>0.005</minDepth>
  <kp>3e2</kp>
  <kd>1</kd>
  <maxContacts>5</maxContacts>
</gazebo>

Since the gripper fingers are effort controlled, I've had to reduce the kp value considerably to have sustained stable contacts. My usage of the gripper hack looks as follows:

<gazebo>
  <gripper name="${name}_grasping">
    <grasp_check>
        <attach_steps>5</attach_steps>
        <detach_steps>10</detach_steps>
        <min_contact_count>1</min_contact_count>
    </grasp_check>
    <gripper_link>${name}_left_gripper_link</gripper_link>
    <palm_link>{name}_right_gripper_link</palm_link>
  </gripper>
</gazebo>

Any advice to get this working would be appreciated. Thanks!