A 30 year old hired late November at UA will retire as a 900ish number as of now. They’d be in widebody captain range for their last 9 years.I don't think its a bad idea to leave. Delta is a great company but nothing beats living in a base, especially when it's a city you want to live in.
Maybe someone at UAL can chime in with what seniority you'd finish your career there versus staying at DAL to help you evaluate what you're giving up.
And wow… just to show how the hiring spree changes things… it’ll take a new hire today 10 years to reach the seniority it took me 4 years to get.