I'll say this much: I appreciate that you tried to release 1080p60, but I am yet to see it succeed. I was watching the "Clash for Cash" between Virtus.Pro and Astralis the other day (Friday?), and it was in 1080p60 on both YT and Twitch.
I eventually left your service to go to YouTube to watch there, because it was stuttering to the point of un-watchability on Twitch, and buttery smooth on YT.
you might need to tweak the config a bit
I gave up using Twitch on a browser, it just sucks (and they keep adding more bloat, weird page refreshes that often load the videos twice, notifications that I have to close every single time unless I'm keeping their cookies permanently)
One thing I'm sure is that it uses way less CPU and helps with my ISP throttling because anything 720p60 and above is a problem if I'm using a browser.
There are options to modify the buffer, reconnect and more but I almost never change my config except for hls-live-edge like once a year (for something that is not Twitch).