Personally I think the safest way, if you can do it, is to set up the new tank about 2 weeks before breaking down the old tank. Do a water change from the old tank, and use the 10g you remove to partially fill the new tank (fill the rest with fresh mixed SW). Put your sand in the new tank, allow it to settle, put some fully cycled rock in your new tank (a couple pieces from your current tank, and new pieces that you've cured ahead of time in a tub with a heater). Wait about a week, then start transfering 5 gallons of water between the tanks every day or every other day. After doing that a couple times, move all the livestock and rock to the new tank.
That's how I moved from my 30 to my 65 (granted it was in the same house). I had no losses or unhappy livestock. It's a bit more work than just dumping it all in, but there are a lot of people who have lost a lot of livestock when they moved, so I think it's worth the extra effort and care.