It is very hard to find accurate P2 transfer rates after searching google, most posts and sites are from like 2005-2008.
Anyway, my P2 H series (360Mbps) card transfer speed from my camera via USB 2.0 is a horrible 15MB/s. That is something like 120Mbps......WTF? I plugged the same P2 card into a laptop PCMCIA configured for P2, with all the drivers and Panasonic software installed......the laptop actually comes from a TV station. I got the exact same 15MB/s. This testing was done with a 1 minute DVCPRO25 clip, and I want to add that the transfer started at 8MB/s, and slowly climbed to a maximum of 15MB/s, but was more in the 12MB/s range. So 1 minute of DVCPRO25 takes 15 seconds to "ingest" or transfer.
Fortunately, I render right off of the P2 card for storage, and rendering times being much slower than the transfer speed, this isn't a major concern at the moment, but hey, WTF is up with these speeds? I ended up buying a 16GB R card on eBay for $150, figured the slowest cards available are still as fast as I am going to be able to get.....would a new A or E series card over USB 2.0 or Firewire actually exceed 120Mbps from the camera or PCMCIA to my laptop?
I just switch the 15 foot USB cable I was testing with to a 6 foot one, and my transfer speed now averages around 19MB/s, about a 30% increase.......I guess that is a slight difference.....unfortunately, I require the longer cable run, so I am stuck with the speeds I am getting.