I can immediately see uses for the Imp Familiar, and Ring of Curses works fantastically with him. That gives you nice control options and reasonable damage options.
The Orc Sergeant seems harder to use effectively because there isn't a discount ring that works with him on a ton of spells you would want him to cast, and the range of attractive options is more limited. The main options that seem decent are Defend, Standard Bearer, and Fortified Position (and I don't really like Standard Bearer or Fortified Position in many lines of play). Well, and maybe Battle Orders. The thing is that you don't really want to cast Battle Fury or Flank Attack on a creature until right before it attacks. Same with Charge, Perfect Strike, Piercing Strike, Power Strike... Running into a Tanglevine or other control spell after already casting a command on a creature is just horrible. So while I think Gurmash can be useful, it will take a lot more thought to get him to pull his weight. You can basically cast whatever curse enchantment you want with Sesyrix, and it works great.