It's our host, they must be encountering some bullshit somewhere on the pipe. Our server box is an absolute beast (we're currently at approx: 10-15% load lol - WOW) and our service is 100Mbit (top-notch for Toronto). So it's out of our hands, at the moment. We've gone through these spurts in the past, and they've always been addressed.
We'll just have to (for the time being) lower our sv_mincmdrate and sv_minupdaterate to 70 so people can bounce between 70-128 to address choke. It's really not going to have an impact on registration (using lower cmd and update rates), so it's no big deal, I feel.