I don't own a Lumia 1520. But, I've just started reading up on it the last two days. I'm totally in love with my Microsoft Surface Pro 2 and I currently have a BlackBerry Q10.
This weekend I picked up a Netgear PTV3000. I immediately updated its firmware and hooked it up to the TV.
Without any driver updates (on my source Q10 or SP2), I was able to connect wireless with my Q10 and (separately, not concurrently) with my SP2. The 1080 display quality actually surprised me from the SP2. I was able to get about 40 feet away. Line of sight, distance, and interference may affect the stream. For example, a microwave oven or other BT/WiFi traffic.
The PTV3000 establishes a 1:1 wireless communication with the streaming source - so internet access or router access is not required. This might be helpful if you were presenting in a conference room where there was no network, or a classroom that is out of reach of WiFi and cell signals were weak. If the source device contained the video (hard drive, SSD, SD card, USB Drive, or PowerPoint, etc. you would be fine. Streaming from the cloud would, of course, require internet or network access from the source device.
My son hooked up an XBox 360 USB controller to my Surface Pro 2 and played Asphalt 8 via Miracast on the TV with no lag issues at a distance of about eight feet. Frankly, I was shocked. While it is best for streaming music, HD video or presenting - gaming and typing isn't out of the question.
All this to say, I believe that the 1520 contains the technical requirements to perform the same way as my SP2 and BBQ10 performed. Lumia 1520 drivers or firmware updates may be necessary to establish a connection between the two. Not sure. I want to try it. I am sooo tempted to get a 1520 so I can really be productive - enhancing my mobile reach. It looks like a beast compared to my tiny Q10.