The one thing that no one has mentioned is the mess!  Cutting metal vs cutting wood creates two different types of chips.  Metal requires a coolant system with some type of recovery system, where wood requires a dust collection system.

I have worked with both and when I purchased my router I made the decision to stay with wood, plastic, etc. anything that a dust collector will take care off.  After spending 17 years as a machinist I'm tired of the watery mess.

Good luck on your build, please post pictures, that's how we all learn.

Chuck