I’m a mac user and work mainly with Final Cut Pro, but also some AVID and Media100.
When you capture with FCP it capture exactly what’s on the tape, in other words, a digital copy.
I would be surprised if Avid didnt have the same technology. What you have on tape is what you end up with on disk.
Ofcourse, this method only works if you capture thru a firewire cable.
When you view captured mtrl on a computer monitor it always looks abit odd, different colorspace/visible interlacing,
so before you judge if the quality was decreased, make sure you have a TV-monitor hooked up to your computer so you can see how it really looks!