I see different people talking abou editing the sony hdv (Z1U) footage via decklink hd ,multibridge etc...
What is the benefit of this rather than via FW to PC with a cineform approach?????

I think the systems you are referring are you used to test whether
it is possible to get some form of uncompressed high quality signal
out of the camera via an analog capture method.

The key benefit is that this workflow works, and it works just like any other High Def capture session like with HDcam. You can capture straight into the format you want, like Blackmagic or uncompressed HD. You don't have to spend time converting MPEG 2 to some other format and you don't loose timecode. The downside is that you need a lot of expensive hardware: a fast disk array, a HD card and an analogue to digital HD converter.