I will only suggest adding voices to MPF and/or Vortigaunt. Citizens tend to spam the voice commands, especially new players, while MPF and Vortigaunt require you to at least be experienced with HL2RP, and not a 'newbie', before you get the whitelist, and access to the voice commands.
So, support to MPF and/or vortigaunt voice commands, but -support to citizen voice commands.