I think there will be problems if you move the default runtime after installing.

You can have multiple runtimes from Poser 5 and up, and any extra runtimes you create can be moved. You'll just have to attach the runtime again, or Poser won't be able to find it.

Mostly, Poser is pretty forgiving about file locations. For awhile, they were putting clothing in the Props folder, even if was a figure.