There are two things to know about the regional airline industry:

1) Past results do not guarantee future performance. Upgrade times are meaningless to a newhire, they apply to someone hired 3..4..5..etc years ago. Not you. I'd only pay attention to it if there is something out of the ordinary going on (ie: its going backwards).

2) Jumping from one regional to another only prolongs your time at the regionals. No one knows the future well enough to pick tomorrow's winners and losers. The only time it makes sense to change is if you're employed at an obviously sinking ship.