Well, thanks to you, AMD VCE is absolutely a viable alternative to x264 for streaming. However, as the bitrate requirements are higher with AMD VCE to produce the same video quality as x264, 720p 60 FPS streaming isn't really viable with AMD VCE for non-partnered Twitch streamers. You can do it, but it looks pretty bad at 3000 bitrate. It looks acceptable, in my opinion, at 3500 bitrate, but buffering will definitely be an issue (at least, as of September 2016).
Recommendation for non-partnered Twitch streamers looking to use AMD VCE: If 60 FPS is a must, as it is for me, and you like the performance improvements that come with using GPU encoding, as I do, I would recommend downscaling from 1920x1080 to 960x540 and using a maximum of 3000 bitrate. Alternatively, stick with 720p 30 FPS.
720p 60 FPS 3000 bitrate using the AMD VCE encoder looks roughly equivalent, to my eyes, to 720p 60 FPS x264 superfast with somewhere around 2500-3000 bitrate (ie. not good). GPU encoding is great for people who like to stream competitive first person shooters and want the best performance possible (at the expense of stream video quality, unless you're partnered and are able to increase the bitrate beyond 3500).
