It all boils down to what drives you. QOL and good seniority? DEFINITELY stay at your regional, especially past age 40. At that age, there is simply too much at risk in jumping ship. Of course, being at a regional that depends on its major is risky in itself, but a bird in the hand is worth.... On the other hand, if you are a person that places all of your value and self-worth based on what and where you fly, staying at a regional will make you miserable for your whole career, as you will be constantly suffering from "grass is greener" syndrome.
I've known both types. I have several friends who wouldn't DREAM of moving on from a regional. They simply have it that good, and I don't blame them one bit. Raking in close to $120K/year, weekends and holidays, a bunch of vacation, flying turns.. who in the heck would want to give that up for an uncertain future? Too much to lose. But then again, they've been there over 10 years so it's an easy decision.
Me personally? I would be one of those whack jobs that would give up 10+ years at a regional to move on. I guess I have a spirit of adventure and a desire to achieve a dream fulfilled of flying at a major. Yep, call me a geek, size envy, whatever... I never envisioned myself flying an RJ between DSM and ORD for the rest of my life. I always wanted to fly the longest possible routes in the biggest metal across the most vast distances. I was lucky enough to make it at age 26 after a year and a half at a regional, never even made CA. But then again, that was in the crazy 90s when every major was desperately hiring, turbine PIC wasn't even a requirement at AA. But I'd still be trying even if I was stuck at a regional today. That's just me, and most of my super senior regional friends tell me I'm delusional. Maybe, maybe not. Just be sure to identify what you really want before making a decision that you won't regret.