2011 is ancient. I have had a Haswell MacBook for a year, and it's near silent at all times.
Eh, not really. 2011 is the first year they introduced the sandy bridge i5's. Moving to a 2014 would only gain me around 11% more performance according to geekbench.
Geekbench
Early 2011 (i5-2415M): 2177
Early 2014 (i5-4260U): 2430 (+11.6%)
Passmark (single/multi)
Early 2011 (i5-2415M): 1333 / 3215
Early 2014 (i5-4260U): 1562 (+17%) /3650 (+13.5%)
So you can see, paying $1500 for a 11-17% upgrade, depending on which stat you look at, isn't really worth it to me.
That said, I WOULD really like: a retina screen, USB 3.0, and better HD5100 (vs HD3000) graphics. But they aren't terribly important to me at the moment.
The BIG jump was from 2010 -> 2011 where they went from the Core 2 Duo's to the i5's. For example, that was a 41% jump in single threaded performance, and nearly a 100% jump in multithreaded performance for the base i5's!