How does the current opportunity fit in with the OP's long term plans/ambitions? What is "the plan" for when the OP's kids are at secondary school or uni or when they leave home? Would the OP be happy to be still in their current job in 10-15 years' time or would it be restrictive/limiting/boring/underpaid, etc?
I took the plunge to take a highly demanding, highly paid job with a long commute. Yes, it was a very hard few years, but I regarded it as an investment in myself. It enabled me to escape from the "comfortable but boring" jobs I had near home which had no future - I'd have been doing the same 20 years later - no thanks!
Due to the experience/contacts in my high pressure job, it enabled me to move into a slightly different section of my profession at one of my employers' clients - a job I'd have never even got an interview for if I hadn't already got a foot in the door by working there one day per month for my employer. Again, it was a demanding but highly paid job and I only lasted 2 years.
BUT, again, the skills, experience, contacts, I made during those 2 years meant that I could start my own business. Again, hard work and long hours, but once it was established, I now earn a very good living working flexible part time hours. All on the back of taking the plunge, using each job as a leap-pad, and using the experience/contacts I made along the way. If I hadn't done it, I know I'd have still been working in a local crap firm, comfortable but boring, but with less income and still working longer hours!
To the OP, I'd ask how do you think you'll feel in 10 years time if no other opportunities come along and you're still doing what you're doing now. If that fills you with dread, take the plunge. If it sounds good, then stay where you are. There's no guarantee of a similar opportunity coming along again!