I understand that other than some churn at the very bottom, nobody ever leaves... so seniority progression would depend on upgrades, which mostly depend on retirements (maybe there will be attrition over the next few years). I personally never applied to JB for that reason, and also due to the risk of being in the only west coast base, and a small one at that. But somebody from JB could elaborate on that better than I.

There is no conceivable difference between JB and AS which would cause me to do a transcon commute long-term, or even risk having to do one long-term.