Can't you switch jobs easily once your I-140 is approved, without worrying about losing your spot in the line (priority date)?
I've known people at my company with approved applications, that left to work elsewhere.
I've known people at my company with approved applications, that left to work elsewhere.
However, if USCIS decides to deny the new PERM, or ask for additional evidence, or who knows what else - you could lose your spot AND lose your ability to work and have to leave immediately. There are many things that could go wrong - the lawyers could screw up, Congress might change the rules, your new company might decide to withdraw the I-140.
It's a risk, and the question is your willingness to take that risk. If I get offered a job where I'm getting paid more that $220K, I might take that risk. Below that, it's simply not worth it for me. And I'm not alone in this.