afang - I notice you posted this after I responded to your message in the NW forum so I assume you didn't read the thread that I referenced. NW doesn't do mid-year upgrades for segments but they DO issue elite status annually based on segment traffic.

The other problem that you should remember is that the programs keep changing. I don't know if you are an elite currently on NW but if so, CO won't comp you and you'll have to start over from scratch. Also, if you have miles collected on NW you can't combine them with CO miles for travel. Think carefully before you switch -- you may not gain very much and end up a year later on programs that are quite different from when started, with non-combinable miles split across two programs.