I'm a fan of Shotput Pro, this ingest program is great for P2 and SxS and pretty fool proof for transferring footage to up to three external drives. I've never had any issues with loss of data using this program.
I normally either do the transfers myself, or one of my sound persons or engineers do it. I've also had my editor do it when on set and I've even had a couple of producers do it who were savvy with P2 transfer. Most of the technical people on my crew know FireStore FS-100's and P2 offloading. I don't clear the cards or FireStore until I've previewed some files off of the drives. I've had a twenty something camera assistant/data wrangler do it as well, but I knew that he was better with computers than I will ever be.
Jeff Regan
Shooting Star Video
http://www.ssv.com