The IPTC interface for PM is miles better than LR, it's rendering is faster and, as Patrick says, there isn't an option to ingest locked files only in LR, which makes in camera selection a bit pointless. PM also has a much better (ie integral) short cut facility for captioning (Textpad).
At the moment my workflow is:
Drag files to HD
Select with Faststone (as fast, if not faster than PM)
Import selected to LR with preset IPTC template (& develop setting depending on situation)
Edit files (crop, straighten, levels)
Caption
Export
I suspect that I'm going to be heading more towards PM in the near future, but still like the LR approach. A great deal of the decision between the two will be primarily down to speed of transmission requirement.