Personally, I think upgrade is much easier for people who have flown multiple types for more than one company (this includes Mesa folks who have flown the Dash, 1900, ERJ, and transitioned to the CRJ). The folks that struggle are the ones who have been sitting right seat in a CRJ-900 in CLT/PHX since they finished San Juan with 250 hours a decade ago--THOSE are the people you gotta worry about--not the furloughed, fed-up Colgan/Comair/RAH/9e FO who made a lateral transfer solely to take a shot at a quick upgrade.