Doing the rehab yourself vs paying somone

[Casey Walker]

I am a contractor and I own a duplex.  

My understanding of the tax law is that I can't write off any of the work that I do on my own investment properties.  What are your thoughts on trading labor with another builder/investor so we can each legally write off the labor?  

What is the saving?  Just the 25% in income taxes on his labor bill?  Or is there more?

What is the negative?   

Thanks