Should I Leave My Job For More Money

I really love my job. I love what I do. I believe it has meaning. My coworkers are mostly awesome. Our "clients" are awesome. I've gotten 3 promotions in 6 years and doubled my salary. I have a young child at home and they are understanding of the demands on my time. My office is 20 minutes away from my home. I have it good.

That said - I'm kinda underpaid. I recently got an offer to make 20% more. We don't need the money to survive but it would mean paying off debt and being home owners a little sooner which would be nice.

I'm torn. I'm nervous I won't like the new job and new coworkers as much. I'm nervous they will be less flexible and I would have to sacrifice my family time more often. There is opportunity for more money and more experience but is that worth it?

If anyone has made a similar decision I'd love to hear how it turned out. Would love to hear from anyone but especially working mothers.

UPDATE

Wow, thank you all for the advice. I've read and thought carefully about what each of you said. I think I didn't realize that 20% is not that substantial. I've taken a large pay cut before for my happiness which is how I ended up at my current job in the first place. Since then, I've gotten married and had a child and I guess I felt a certain obligation to earn as much as possible. But I agree with those saying 20% is not worth the uncertainties.

I'm still going to go to the second interview just to see if I really hit it off with the people or they have some kind of amazing work-from-home option that would significantly increase my quality of life but outside of these two things the 20% increase alone is not enough to take the job. (It was offered unofficially pending a second interview that they said was a "formality".)

Mini Update

I'm continuing to read your responses and I will still take the second interview with more of an eye at interviewing them. I'm curious how many of you that say you would take the risk have a young child at home?

Also, I would never use this offer to leverage a raise at my current place. I believe this is a great environment because people love the mission and are generally the type to forgo a little extra money for the sake of fulfillment. It's competitive to work here but not because of the money. I feel that kind of move would be frowned upon.