For your usage, no.
In General, I think a jump from 3 to 4 is a better deal than 2 to 3.
2 to 3 gets you the retina display and 1GB of RAM.
3 to 4 gets you a (significantly!) faster CPU and GPU
Depends on what's important to you, really. For your usage, the retina screen might be the most important feature and in that case you're pretty well off.