We shoot with the Sony Z1U and Firestore, I also have a Sony HVR-DR60 inhouse for testing. Capture off the tape as HDV. The quality from all of these will be exactly the same, unless you change the codec, i.e., recompress using a different codec. But, I would keep in HDV, if you want video.
Right now, even with the latest FCP6.0.2 release, from what I can tell you will have to convert M2T files using MpegStreamclip or other encoder/converter, which will affect your quality and other possible problems.
Capturing from the Z1U from tape has been flawless. Using Firestore has not been, and using the DR60 means other processes you shouldn't have to deal with at this time.
I will be testing with and learning more about the Sony DR60 today and if I think if it, I will come back and share my results!