I always agree with dedicated servers since you have so much more control over them and you are less likely to get hit by something from another site on a shared server.

There are reasons some hosting companies charge more for bandwidth, co-location, or servers. At least with those companies that have been around for a few years with no negative comments.

Another choice, if you are not ready for a dedicated server you can always find a place that offers a true VPS (virtual private server). Since you already have a dedicated server you know how important quality and service are.

I'm used and purchased Cogent before and I can tell you the issues first hand. Though I had a 99.999% uptime and my MRTG showed very few issues I was able to run tests from different points around the world. No matter where it was.. Cogent traffic took longer and had more delay then any of the 6 Tier 1 providers I use. Then again...the one client was just focused on price and it worked for them.

So... the answer always comes down to value and price. If you dont' need the valued added benefits from a dedicated server on a tier 1 provider (multi-homed, quickest path routing) a shared (or VPS) will work fine till you are ready to upgrade. If it costs your $200 more a month to get $20 more in sales.. don't upgrade.

Fast site loads = more happy surfers that tend to stick.

It is a hard choice but ask yourself what you expect as far as speed and uptime if you are the customer surfing your site.