I also went with the 450 since I don't need a bigger ssd. It will do most of the things I need at school and don't game. And use cloud for storage. If you did need somethinteresting super GPU intensive like rendering (me) I don't think the 460 will be fast enough nor is the 16gb ram. So I decided to save that money and build a hackintosh for more intensive things. Why have something in the middle when you can have something on the go and something much faster.
I did that when I had an Air. Light and portable on the go, and powerful hackintosh at home. Eventually I hated the lack of power on the go, and I hated how updates would sometimes mess up the hackintosh. YMMV.