Would this be a good reason for child domains?

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http://serverfault.com – I am building out a sharepoint environment, which would have dev/prod domains. However, I will also be hosting a number of infrastructure servers in the network such as WSUS, DHCP, WDS, etc. I am thinking that I can create two child domains under a parent domain called say INFRASTRUCTURE, which comprise of the respective dev and prod sharepoint environments. Is there any flaw in this design? It's either this or 3 seperate flat domains under the forest. Thanks (HowTos)