Regarding managed hosting versus colocation (as I understand them), well I am agnostic at this point. I believe the client is leaning towards colocation but I favor the most robust solution and that might be managed hosting.
I am looking for factors such as: best connectivity and why, stats or other measures of performance (technical performance, operator performance, and contractual performance), most competent network engineers and how one might judge that, best relationships with upstream providers, etc. The idea is to find a stable solution with a partner that can help us quickly diagnose and alleviate connectivity problems including network attacks.
I'll give you a for instance. For instance, Rackspace seems very attractive in many regards. As a private company however, their books are closed and presumably that leaves some additional risk that they won't be able to perform compared to a public company (seems a bit funny to write this a week after enron cratered.) How would a savvy player address this risk?