Job offer decision and weighing up options

I going for a second interview for a role and need some help in weighing up the decision because its a step back in pay and responsiblity but with an organisation that leads in the area and has good growth which has a lot of appeal to me. It would mean going back to the private sector after 7 years in the development sector working for the UN. I am looking at a 30-40% pay reduction, somewhat lower status and instead of 2 direct reports i will have no management responsibilities. I am in a good financial situtation and am 'frugal'.

With my current role, i am expected to move every 5 years to a different country, and compete for these roles - several of these posts are in developing countries. I have 2 and half years left in my current contract and its in denmark, and my family really like living here.

As i have been out of the private sector for 7 years I consider it very lucky to have got this far in the interview process because I have been out of that area for so long. I may not get this opportuity if i wait until the end of the contract because my relavant previous experience will be too outdated. 

I'd love your thoughts and feedback on my next move.