I have just tried MTP and it works very well. 1.3-1.5 MH/s per card for my 570/580s. Running low core at ~1080 MHz.

12 GPU rig power consumtion, 1080 W (8 GPUs mining MTP, 4 cards (4 GB VRAM) idling). Total 11.75 MH/s.

Thanks for a great miner!