Really enjoying the Coiltek 10x5. Perfect in between coil for the stock Minelab 11 incher and the 6 inch "hockey puck". Deep too, both of these Mercs were a foot down.
I have the 15 and 6, and of course the 11. The 15 spends the most time on my machine at the moment. The 11 is a tad lighter and the one I use in the water at lakes, the 6" i'm too impatient to swing often, but I'm keeping it. I'm really tempted to try out the 5x10 Coiltek but PastorBob beat me to the used one for sale here recently and I just can't seem to cough up the dough for one.