To answer your question about your client not needing HD, the P2 cards capture resolutions other than just HD which will be better than regular DV (for example DVPro50), which is the only resolution you can record onto the tape. So if only from that angle, your client will end up with a better picture.
When you record to tape with this camera, you’re recording using DV. There is no option for better resolution.
If I understand your question correctly, you cannot record HD to the cards, save it to your laptop and then transfer the HD resolution to the tape. The tape is just for DV, so you’d downgrade the picture dramatically.