Me? No, I'm rated and a captain, but FAR 61.51 (e) does allow someone who is not the Captain (designated PiC) to log PiC time when "acting" as the PiC. For example a type-rated pilot may not be the PiC, but can act as the PiC, sign the flight plan, and log the time. Cannot do that with a SiC type, though. Essentially, you are operating with 2 PiCs and they swap legs, for example. Yes, I don't agree with it, but it is the FAA counsel's opinion.
Yes, there is confusion between FAR Part 1 definition of PiC and FAR 61.51 with regards to logging time. Being the FAR Pt 1 PiC does not preclude a pilot, who is not the PiC from logging PiC time for purposes of meeting flight time requirements under FAR 61.
GF