You may want to think about comparing a new 5.0 crate motor vs the sc cost wise and ability to handle more power adders down the road. Just saying.

 

In the end the "safer" decision would be to get an '11 unless you run the risk of not having money to afford the car payments. You'd be buying a newer car, lower miles, fast out of the box...the list goes on. Of course, to each their own in their own situation.
It really depends how attached you are to your '05. Before you make a decision one way or the other just ask yourself if you will regret not going with the other. Hope this helps.