Okay, well I did my own tests.
I digitized my last job with y/c and re-digitized it again with firewire DV. First of all, when digitizing with y/c I really missed having the deck control or time code I had with DV. The digitizing did not automatically stop at the end of video like it does when digitizing with DV, y/c stopped at end of tape.
Next I put both clips on time line and cut between. I noticed dramatic differences. The y/c audio was much too low, also the video was more saturated, darker and no detail in blacks. Over all, I prefer the DV firewire.
Thanks to everyone who responded.