Yes, but they make up for it with a higher cost. Also, they should leave something usefull behind when destroyed. (Not the steam grafts, the two other ones) Such as magic stones, gems, or something similar.
A magic stone by the way is a one shot, relatively weak, magic item that can be activated as a standard action by anyone. The spells in a magic stone are of level 0 to 2. popular spells in a magic stone include the following: Aid, Mage Armor, Cure Light Wounds, Light, Darkness, and, Snilloc's Snowball Swarm.
But if I where you, I would go with gems... That should make up for an eventuall higher challenge that the grafted creatures become.
Later,