We have cogent in the mix, and I do have to say one gets what one pays for... They are a no redundancy, no extra capacity kind of shop... This often is noticeable when they have fiber cuts or equipment failures, it also results in a lot more service affecting maintenance than our other providers.
That being said, we have several 10Gs to them as one of our five upstreams, we mostly use them for on-net traffic and a couple of selected peers where they seem not to have congestion issues. My biggest bone to pick with them though is their incredibly crappy BGP community offering. They have no selective (ie per peer) announcement control options which severely limits our ability to use them more since we end up sending their "perpend to [all] peers" community instead of just prepending to the peers we don't like the return routes on. Thanks, John @ AS11404
