If you really need the mixer control a lot, it is surely interesting, but the 608i is also considerably more expensive than the 600. The audio features (speakers, wattage etc.) are identical.
Thats very true... most people have a seperate mixer..
but the idea behind the 608i is one i can see many people embrace in the future..
According to some tests the Nano series are quite addaptable to your preferences. And with the right settings you can even archieve a neutral sound character which might be what you prefer ... this goes for all 3, 300 600 and 608i