You may be asking.... is there a performance improvement just from the new driver, without doing anything else? I don't know, but I can start asking around, see if I can get some light on that.
Is there potential improvement, if you take advantage of OpenCL 2 features? For sure.
One blog we have up has comparative benchmarks: http://developer.amd.com/community/blog/2014/10/24/opencl-2-shared-virtual-memory/
a binary tree search of 5M nodes took 18 milliseconds using SVM vs. >310 milliseconds without.
There might be some benchmark data in the other OpenCL 2.0 blogs, but if so it has slipped my mind.