Other 121 carriers like guys with 121 time and transport cat. time. It will make it easier to get on at a "prefered regional," but with the way things are going at most regionals that would be a stupid move. After 12-24 months at a lot of regionals you will be able to upgrade and get your 121 PIC time. Why leave and start all over again? Get the PIC time and move on. 3 to 4 years at a regional or 6 years?
My 2 cents