JRKO,
Perhaps I can help by telling you my workflow.
After I apply develop settings to a raw file, I use control-E to bring up the export dialogue. Export a copy to PS as a Tiff, Prophoto, 16 bit, and stack with origonal. LR creates a new file in the same folder as the origonal with the same name but as a Tiff, then opens tis file in PS.
When I am done with the file in PS I SAVE the changes {control-S} . This writes the changes back to the file, which remains a Tiff. It will even include any layers.
If you wish to use the file for another purpose or to save it in another file format you can then do a Save As, but always do a Save first.
When I go back into LR, there is is my -edit.tif with the PS changes applied.
This is with LR 1.4, no changes from any of the earlier versions.
If I may respectfully suggest, don't use the PSD format. Keep everything in Tiff, Prophoto, 16 bit. I think the problem arrises by changing horses in midstream, so to speak. Keep it simple by sticking to one file format instead of doing a mix and match thing. Jeff Shewe has explained in other threads on this forum why Tiff is preferable over PSD.
HTH
Rich
Edit- LR does not support the Quadtone mode. After you apply your Quadtone, change the mode back to RGB.