[oldE]

"I switched jobs, primary motivation was the lack of pay and promotion"

Matt,

Larry has a lot of good points. I think you already have in mind your old employer didn't begin to value you until you left. They were paying you what they could get away with, pretty sure they had you.

Then you made your statement by moving and now they have a vacancy, they know you are tempted by their offer. Like others here, I feel you should have a candid talk with your 'old firm' and let them know up front you are worth more than what they are offering. If you are getting that for "a mundane desk job driving metrics and updating databases", then a position with real responsibility should be worth more.

Also, with your current employer, if you do make the switch back, let them know the position wasn't what you thought you were getting in to. They're not going to like it, but it is far better to be doing something you like.

All the best.
Les