If the lowest rating is above 5Nm, I don't think a torque wrench is necessary for a few adjustments. Just don't be paranoid about making sure it's tight enough, and don't tighten it as much as you can with the long arm of the hex key.

I don't think a whole torque wrench is necessary just because you own a few carbon components. The Ritchey Torque Key is a great piece to have though.