If you're just using Warriors, then yes you should drop some to make room for Immortals, or possibly Destroyers.
You'll find while they're really hard to kill, you might have some issues dealing out pain. Warriors absolutely suck at mobile firepower, something that Immortals and Destroyers are absolutely GOD at. Plus AP5 doesn't always cut it, especially against those Firewarriors/Aspect warriors. IMHO anyway.
Xhadow