Maybe not
You might want to continue your policy of avoiding 1st generation products.
There have been some issues with the Model A retinas; whether you would suffer this is a roll of the dice. All the more as various screen issues have been reported popping up months after purchase (and beyond initial inspection, if from a store, and easy return). There seems a fair chance Model B retinas will experience fewer such issues.
The advent of Haswell should help the relatively underpowered 13" retinas most, but still a consideration with the 15", particularly regarding eventual resale.
$300 seems like a decent discount, otherwise. Although as it is built in, ideally one would want 16GB of RAM, especially in a 15" model where it may be more likely used.
As halfway inclined, you might want to skip this.