It's difficult to know what might be causing your issues, from here. Clusters should just work like any other deformer, and should scale properly with the your rig (if it's parented under there). It sounds like there's some double or even inverse transforms going on with either your clusters or your cloak-model...
There's a few things to try:
- Try to check off the '.inheritsTransform' attribute on your cloak model
- Try the same for the clusters.
- See if you've got any negative scale values on your th nodes in your hierarchy, ideally it should all be positive and even better 1, 1, 1.
- also make sure not to parent stuff to geometry, this generally causes headaches, much better off using constraints for this.
Otherwise post a few screenshots, so we can have a look at it..