A BIT OF HISTORY

The first gpu miner for groestlcoin and similar was sph-sgminer by phm. Optimizing the original implementation was trivial (almost 3x the speed could be achived!), so probably there are tens of optimized versions around, many of which have been kept private: mining groestlcoin and similar was always unfair for most people, at least for non-devs.
Hopefully this kernel will end this and should also level the field between amd and nvidia.
I believe my version is faster than many of the other kernels because of the time I dedicated to it and the thousands of tests I did.

FINAL ADVICES

I suggest to keep "good binaries": make a backup of the fastest .bin files you have, so you can recover them in case of driver problems.
Also this will enable you to get 1 o 2 percent more hashrate because of compiler variance (try removing the bin and running 3/4 times to see the variance in action).
Or use the provided bin file (see the OP) which should be a good one.

I've experienced lower power usage with catalyst 14.9 compared to 14.6 beta (a bit less compared to 13 but still better). Speaking of optimization, this should be kept in mind: buy a power meter for your miner(s)!
But it looks like the compiler included in 14.9 drivers produces binaries which run considerably slower than older releases. If you are on 14.9, use the provided bin file instead of the kernel source in .cl format.