I've been considering the 6GB iPod Mini some more, mostly because it will hold all my music and then some - the 4GB nano will just barely hold what I have now.
If anyone else is having this dilemma - trying to choose between a mini and a nano - I'd suggest you make up your mind post haste. As far as I know the nano has been introduced as a replacement for the mini, the upshot of this being that the mini will soon be phased out and become unavailable for purchase. Least that's what I've heard.