Well, if you use OpenCL anyway where’s the advantage of bringing in a big x86 card?
It appears that the Xeon Phi processors are quite weak compared to GPUs in various kinds of computations.
Of course the instructions are different, so there are some things which are fast on a x86 (the Phi) and require lots of cycles on a GPU.
But it looks like for most Monte-Carlo algorithms GPUs win.
Cycles is a monte-carlo algorythm, so it’s likely it would perform better on GPU than on the Phi.
The only advantage it surely has would be that, since the Phi is a x86 core, you can use any programming language you could use on a x86 cpu, so those developers who don’t like OpenCL can pick a language they are more comfortable with or which is more fitting for the job. If you just use OpenCL, you’re losing this advantage.