No worries.
According to specs the 2011 Quad Core i7-2860QM still has a little more juice compared to the Dual Core i7-5600U, granted it has more l3 cache and 2 more cores. The impressive part is the i7-5600U is using 1/3 of the power and has more advanced iGPU, even with lower Turbo clock I'm betting the 5500 > 3000 by a large margin.
With Intel's schedule behind it seems the U series is making a big splash in the PC Windows notebook world. I'm betting the majority of even professionals would be OK with those configs, like the T450s from Lenovo. They're really going bonkers over battery longevity but one has to wonder if Apple will take a hard stance on the 15".
One has to wonder, would you take a Dual Core Broadwell and double your battery life or would you wait till Q3 or later for a Quad Core Broadwell with maybe an hour longer batter life but doubling your cores. I've been using a late 2013 13" rMBP for traveling and a late 2013 27" iMac (maxed out). I was hoping to consolidate to a single machine (perhaps a 15).
Guess it's late and I've been coding all weekend and starting to speak in Backbone (runs and hides). Guess we will see what happens today!
Added: Here's the benchmark from CPUBoss:
http://cpuboss.com/cpus/Intel-Core-i7-5600U-vs-Intel-Core-i7-2860QM