It seems like XMR mining is better with GPU... Maybe I'm mistaken, but one Radeon HD7990 gives over 1000 h/s (this opinion is based on this post). For example 3 x HD7990 could easily beat 2 x E5-2699. And 3 x HD7990 are MUCH cheaper than 2 x E5-2699...
So, it seems like XMR is definitely a GPU coin...