Good advice. I was actually a back-end engg for the first few years of my career. I ended up transitioning into front-end because I really enjoyed it, though I kind of miss helping out in all aspects of the stack.
If you are purposely staying in this place because "the work is good", then make sure that the $10k-20k less that you're making is worth the extra goodness, whatever it is. It's always a tradeoff. Also, no harm negotiating a raise.
In the end, you are selling your services, so don't get jipped. The very fact that you are here is a strong indication that might be.