I don't know enough about your current situation to really provide comment on whether you should stay or go. However, I have found a lot of opportunities and growth in my own career by moving jobs from time to time. You should be deliberate about the choice. Plus you can get much more significant pay raises by moving jobs than by just getting yearly pay raises. If the offer in question was willing to give you a 20% within 24 hours of applying, I'd either be a bit concerned that they're so desperate or I'd push for more money than that. I'd try to get at least a 20% effective raise after all the benefit offset. You can even argue that if their benefits aren't as good, pushing for more money.