good post, analog. i remember coming across Redshift in a search for Ambient a long time ago, but this is a good reminder.
i think coming to an accurate understanding of what Ambient actually is, is a task worth staying with. i liked the Redshift cut, but still it doesn't quite achieve the level of emptiness that marks true Ambient for me. to me it is Electronica.
many kind of use Ambient and Electronica interchangeably. and Electronica is a genre of many sub-genres. there is the whole area called 'Chill', which for many is the same as Ambient, when it isn't. for one thing, Ambient has no beats. it is more empty than full; it suggests, rather than informs. it stretches the canvas on the frame, implies some colors, but stops there. it is a music of restraint, like haiku is a literature of substraction and implication.
another candidate for Ambient that i have been meaning to post is Biosphere. here is a Youtube of one of my favorites by him, Ambient in the strongest sense. to me, that is.
looking forward to hearing others thoughts on this topic.
http://www.youtube.com/watch?v=mjoIOs6OzNc