I was eager to give this service to try because for some reason connection to european Twitch servers wasn't good enough for me.
I tried, but connection quality to Frankfurt server of Restream.io wasn't good as well.
After finding out that Restream opened server in Russia, I was excited because I live in Russia. I thought that at last I could upload stable 3500 Kbps into russian Restream server and stream on Twitch using it.
But, unfortunately, connection quality was as bad as it was with european servers (I was losing around 35% of frames), I really don't know why.
In addition to this I should mention that my connection is enough to maintain stable 6000 kbps connection to Youtube Gaming servers and perfectly stable 3500 kbps (which I believe is maximum allowed by that streaming service) fo Hitbox server in Moscow, but for russian Restream server my connection isn't good enough do deliver even stable 2000 kbps.
I've made two long test streams - the first test was on Wednesday: no disconnects, no frame drops, everything cool; and the second one on Saturday evening: lots of frame drops... So I think restream.io doesn't have enough capacity for weekend (yet).