I'm confused. Is your DH still going to be working in the same place when you move? I know you talked about him getting a different job, but would that be a different full time job, or a part time job? Because I can tell you right now that when gas goes back up to $4/gallon, that extra $300/month is going to disappear if your DH is commuting an hour to work every day.
We moved an hour away from family and friends last year, and it hasn't been nearly as easy as I thought it would be. I still drive over several times/month to see my family, and the cost adds up. I also drive further to shop now than I used to. There are more expenses than I anticipated. I'd sit down and figure out how much it would cost for you to visit your family/friends, and think about how often you'll want to see them. I have a chart on my fridge that tells me how much it costs me to drive to my parents' or sister's house depending on gas prices. Gas is cheap this month, but when it was $4/gallon, it cost me almost $18 for the roundtrip to visit my sister and $13 for the roundtrip to DH's office (37 miles away). It adds up fast.
I'm not saying 'don't do it.' But make sure you're considering everything. Is rent comprable? Will utilities on the apartments be the same? If your DH is planning to get a different job in the new city, will the salary be the same?