Henderson is a tricky one.
He'd obviously be a great option, and you'd assume would start with launchbury.
However, if he's still up for international selection, then we'd lose our first 2 choices at lock for the AIs and 6 nations. Plus neither would get a proper rest in the summer either.
It's a difficult one to make a decision on. Having your players away on international duty is one of the things that a successful team has to contend with.
Saracens have done it recently with 2 locks being selected for England. Leicester used to have Johnson and Kay selected all the time. We've probably dealt with it in the past too (did Palmer and Shaw ever play together and get selected?)
Ultimately, I think you need to have the best players possible in the squad. It not only improves the quality of the starting XV, but pushes others to improve too.
If we can afford him, then I think we should do it