I have, and actually I did a clean install 8.1, the only thing im missing though is the wireless driver which is not supported in windows 8.1 or I dont know how to do it.

Overall pretty good, I mean I dont see any speed differences with win 8 yet but its stable and nice

By the way, I just checked, the Wireless Drivers are seperately available for Windows 8.1 on the Asus Site

http://www.asus.com/Notebooks_Ultrabooks/ASUS_ROG_G750JH/#support_Download_40

I upgraded and experienced no issues going from 8.0 to 8.1. The only driver I have touched is the newest Nvidia drivers. At home I use my laptop on a Toshiba HD TV via HDMI and switch between HDMI sound and onboard sound all the time. I also use the wireless and havent experienced any trouble with it on 8.1 either.

Just to note, I was skeptical about the KillerN Wireless and thought I may have to go aftermarket and replace it, but it has been a VERY nice performer. I have the ASUS PCE-AC66 for wireless on my desktop which is a very nice long range wireless adapter, this allows me to get 5Ghz in my back bedroom from the front room router. This KillerN in this laptop actually connects at 300mbit on a desk right next to my laptop when the Asus Desktop adapter connects at 264mbit. So it is on par with or even better then the desktop solution which speaks highly of it in my opinion.