I have a in-car headunit mirroring setup.
Bought a Measy A2W Miracast dongle a while back and couldn't get it to work with all 3 of my devices (note 2, note 3 and P600)
Then bought a Samsung Allshare cast hub yesterday and wouldn't work either. Figured out if you root/custom rom it breaks Mirroring by detecting flash attempts. After triangle away on the note 2 and 3, Allshare cast hub and Measy A2W now mirror.
Allshare cast works better, less signal breakage and setup was easier. $63~ at major stores right now, $40~ on ebay, $50~ if you have 50% off samsung.com
Measy was 1/3 of the cost, intermittent signal breakage (music was breaking up for a second), and D/C'ed once for no reason. Also there's setup involved. You will set it to either boot into EZCast or EZmirror mode. If you set EZmirror mode, you have 120 seconds to connect before it will revert to EZCast mode (DLNA). You'll have to connect with EZcast app to switch.
Just installed a patch this morning for my rooted P600 (triangle away doesn't work yet and I have 9 flash counts!)
Going to test it out later this afternoon. Will post results and what I used.