I was in a similar situation years ago. I was an F/O at Zantop in the Convair flying a fair amount but looking at years before a left seat would become available. I quit and went to a commuter flying a Beech 99 to get my PIC time. I put my 3 years in as commuter (regional) captain and was hired by a major (at least it is now). I look at guys that stayed with nonsched freight and I am glad I made the choice I did even though they have the more interesting war stories.