I started this conversation with Lance on twitter...
I've tried traceroutes to the twitch servers but always timeout (even when i'm not dropping frames).
I tried running speedtests, which are great when my connection is fine, but timeout as well when i'm dropping frames.
I have not tried other devices on my network during these choke-outs as I try to keep my local activity "clean" to avoid congestion (even tho i've often seen times of my wife watching twitch without congesting my upstream) and keep a high bitrate upstream, and i'm usually taking steps to mitigate the frame losses (lowering volume/turning off music, lowering bitrate, etc) instead of seeing if other devices work.
I've uploaded my stream log (showing just how many frames were dropped today) if necessary, but I would just like to say if my account is being throttled due to my traffic, please at least whitelist twitch.tv so this doesn't ahve to happen.
another discussion has a shaw rep saying the congestion appeared to occur on a peer between shaw and twitch.tv but that they think it has been "mitigated". no. it still happens to shaw users.