The EMG 57/66 set is a great set if you are looking for something in the middle of EMG HZ and EMG 81/85. This set delivers the Clearity and the Sharpness just like the EMG 81 but with a little less gain, with that said this set will be good for both metal and rock but also other musicstyles.
Nothing can go wrong with this set because its a great alternative to other EMG pickups if you want less gain.
I recommend this product