I think once you've made it close to 2nd year pay like you are you'd be crazy to leave. It'll cost you $100k to make a move like that... Maybe more. The legacies have hired a ton of young people and you'll be junior to them. You'll be on narrow body pay for several years AFTER clearing 1st year pay.
Yeah... I get it... We had a bad year, BUT there are reasons for it. Namely a Trade War with China that won't last forever. Despite that we're profitable. If an economic downturn does hit because of the Trade War (or whatever) you'd be furloughed at a legacy for sure.
As for making your life better at FedEx, moving to Memphis is an option and if not then yes your life would get better with Seniority.