Yeah, merged mining kicks ass - I have 50% of my XMR nodes merge-mining XDN and the other 50% merge-mining FCN, good to squeeze a few extra satoshis out of your mining =D
I'm also mining XMG on my spare i7 Hyperthread cores (that XMR can't utilise) at no extra cost to the cryptonote hash rate, I get 3x power from each CPU =)
It is really good, more coins, higher security for the network and the same energy costs!