Hey folks... I've updated RCTools to Version 5.0, main new feature is the "Topo Clipboard" explained in the doc quote below..
Did test this a lot, but should be tested a lot more because there's so many possible sources of error in this feature - so any feedback is appreciated.
4.2. Topo Clipboard
Usage: Make a polygon, edge, sample or point selection on a polygon mesh object, then from the Topo Clipboard->Copy menu, select an existing property (UVs, Envelope weights, ..) to copy from. The properties in the selected area will be copied into the clipboard and can be pasted to a different part of the same or a different mesh using the Topo Clipboard->Paste menu.
Important: The two selections must have the same underlying topology for this operation to work.
Such operations so far haven't been possible because the point order differs in different areas of the model/on different meshes. The Topo Clipboard feature though builds a new temporary point order that depends only on the selected topology and is independent from the internal point order.
Limitations: Topo Clipboard can have difficulties with symmetric topologies. It does a "best guess" on how the intended orientation is, but is sometimes unable to figure out the "proper" orientation. A good practice is to temporarily cut an edge somewhere in the selection in order to introduce some asymmetry. This trick can also be used to deliberately rotate the pasted result, by placing the "extra" point in a different corner.
Copy/Paste Form:Copies the form of the selected area to the pasted area. Orientation of the pasted form will be adjusted to the new area. This function cannot handle mirrored topology, use the "Paste Form (Mirrored)" function if the pasted area is on the other side of a symmetric mesh.
Copy/Paste Envelopes:Copies Envelope weights from the selected area to the clipboard and allows them to be pasted on another area. After pasting, a remapping dialog is shown which allows you to remap the clipboard weights to new deformers, as done here with the finger joints:
There's an exception to the "same topology" rule here: If the clipboard weight contains the deformer weights of only 1 point, those may be pasted to any number of points you like. Paste Envelopes can handle mirrored topology automatically. To get a normalized result, existing deformer weights will be proportionally reduced so the new pasted weights will fit in fully without modification.
Note that in the current version, envelope pasting doesn't work with partial clusters yet.
Copy/Paste UVs:Copies UVs of the selected area to the pasted area. Can handle mirrored topology.
This can also be used to copy UVs between two meshes that have a different point order, but the same topology:
Copy/Paste Vertex Colors/Tangents:Copies vertex colors of the selected area to the pasted area. Can handle mirrored topology automatically.
Copy/Paste Weight maps:Copies weights of the selected area to the pasted area. Can handle mirrored topology automatically. Works also with partial clusters.
.. 
