Well, I would say that digital mixing is a pure mathematical thing instead of analog mixing which is a more physical way of mixing. I know that many of the musicians in here won't agree (especially people out of Netherlands ) but you'll loose dynamics by using digital channels only. I would advice you to use analog signals as long as it is possible in your studio.

Compare DDD with ADD and you'll hear the differences. ADD sounds much more animated as DDD where you'll miss the dynamics. Why do you think do modern studios often use tubes in their equipment before mastering?

For example: I'm mixing all tracks down with my analog mixer. All external effect channels are organized as analog channels. My complete sub-mixing channels are analog channels. So, I'm using the big 'A' of ADD...
Then it comes to the recording (out of the mixer's master channel in to the sound card's AD converters). This is the first big 'D' of my CDs which provides the last big 'D' (yes, it's the medium itself). In my opinion the modern digital systems are absolutely overwhelmed with functions they'll never get fitted...

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Greetings from Frankfurt (Germany),
Sheriff ;-)