I have an SP2 and two miracast devices in use. An iPazzport and Push2TV, I also have the Belkin POS and one other, the name of which escapes me at the moment. I have both desired devices plugged into my Receiver (HDMI x 4 inputs) and both pass HDMI video with sound to the 5+1 system.
The Miracast video works fine with both, but the sound is terrible with the iPazzport and the sub-title lag is abysmal. The Push2TV works perfectly, but it has it's own frailties too. Reliability is not one of the high points of the Push and occasional jerky video is the norm. You may fare better with a msoft Miracast dongle at about twice the price.
Having spent more than enough on Miracast dongles I will tolerate these two. I keep the iPazzport as it woks better with my Moto-X in Casting mode although the sound is nowhere near as good as the Push, but the Moto-X is not happy with the Push.
Since getting a Fire-TV-Stick, I rarely use Miracast now. If Fire had a Crackle app I would be happy, but alas, Amaozn only has an Fire-Tablet Android version.
I may try to side load that to the Fire stick.