Well I have some experience with moving as a child and as an adult. My dad was military and we moved a twice when I was 2 years old and 4 years old. I don't even remember the moves much at all...I adjusted without incident.
We moved again when I was 13 to the other side of the country and I cried for a month. Then we moved back to my hometown and I cried for a year.
Then my husband finished college and got his first job offer in his hometown which is 16 hours from my family. We were living within walking distance of my brother, five minutes from my mother and 15 minutes from my other brother. Within two hours of my mothers family and 13 hours from my dad's. I did not want to move. I thought it was a bad idea because we were moving from a very low cost of living area to this area which has some of the highest cost of living in the nation (especially property taxes which typically aren't counted in cost of living for some reason???)
Needless to say I was a grouch and bitter for about two or three years. It has been nine years now and I still don't like it but I've accepted it and I have decided to make the best of it. We are still struggling because of the economy here and I don't see any relief for a few more years. I have become very close to my husband's family which is such a joy. I have grown to love his mom and dad like my own parents. His brothers and sisters, aunts and uncles and extended family are all great. That makes the whole deal here in Hellinois bearable.
I really think at six and two, your kids will adjust fine. They will talk about their relatives, but after awhile they will set right into the routine that you set. It will be much harder for you and your husband. Things I think you need to consider:
1.) How close are you to your relatives and how much do you depend on them for support and interaction?
2.) What is the cost of living difference between here and where you are going? And especially the property taxes because that really is a big factor that isn't typically considered in those cost of living calculators that you see on the internet.
3.) Do you own your home here and are you willing to wait as long as a year or more to sell it? That is if you have to sell your home...hopefully his company will buy it.
4.) Did they offer you a relocation package that will move you, store your stuff for as long as needed, and provide you with rent while you are looking for a new home? How much will it cost you and how much did the give you? Is it enough?
5.) Do you need the money from your existing home to put down on a new home?
6.) Is there a big cultural difference between this area and the one you are going to? I find that southeners don't have much trouble adjusting wherever they go (except for the cold) because they are very laid back typically and low key. People from the north have trouble going south because of the heat and the lifestyle differences. Northerners typically are very annoyed with the slower pace, the laid back attitudes, and the spreadout nature of the communities down south. It drove my husband crazy when he was young. He misses it now but he's a more mature man with children so now those are things he would appreciate.
7.) If you are going south, do you have issues with minorities? The area I was from was about 65% black if not more. I personally miss the interactions with my black friends and the culture. Here the only black people I interact with are a few at church. There is only one family in my neighborhood out of 400 homes.
Finances I suppose should be one of your big priorities. But I think interaction with your family should also be a big factor. My father's family is in Michigan. That is six hours away and we see them once a year. My family is in South Carolina and that is 16 hours away. Some years I see them twice a year and others just once. We live near my husband's family here in Illinois and I'm so glad they are here. I wouldn't have lasted this long without them. Family is very important to us.
So I hope I gave you some things to think about. And I hope it helps. Good luck!!
We were recently wrestling with the opportunity to move back to South Carolina. It turned out the company wasn't going to do all the things they said they would initially like buy our house and pay for storage and so forth...so ultimately we didn't move. It wasn't worth it. WE would have spent $42,000 to move and then had to live with my mom for who knows how long until our house sold. So we didn't do it. I was sad but it was the best decision.
Good luck!!