I don't have the time to hunt all these down and refactor everything Yes you do. You're just choosing to spend that time on other things rather than pay off so

I don't have the time to hunt all these down and refactor everything Yes you do. You're just choosing to spend that time on other things rather than pay off some of the technical debt (that the framework introduced rather than you). Your decision to just live with the old version will prove to be a bad one in the long term: you'll find it frustrating, your skills will stagnate, new hires will find it frustrating (and will quit), eventually 5.2 will stop receiving patches so your security will be compromised, and you'll miss out on some of the shiny new features in the latest versions. This will get harder the longer you leave it. It's worth investing the time to move with the framework even if the framework is a pain at times.