I move a good bit and often times from 1 side of the country to the other. Moving a larger tank is basically impossible, especially in terms of keeping things alive. So after having to sell/give everything away a couple of times I no longer do larger tanks. Now I stick to tanks under 30 gallons.
In my last move, which was cross country again, I took everything from my 20gallon and put them in 5 gallon buckets. The rocks, the sand, the coral and the fish. Then I drilled out some holes in the lids and ran air tubing with an airstone in each. My SUV has a plug in and I bought a pump that would run full time. AC inside kept things at a good temp. Everything lived in what was about 8 days in those buckets, taking them into my rooms at night(got weird looks explaining to the clerks I'm checking in with fish).
But then they didn't go back into the same 20 gallon when they got here. While checking out one of the new LFS looking for a new/better stand before I filled it back up, I saw they had a 25g cube w/ stand for more than half off. So I bought that the day I moved in, set it up and put all the livestock etc from the previous tank in it.
To me it's still the same reef despite being moved and getting a new tank, and it's going on over 2 years. But I guess in terms of how long it's been as it sits now, then it's only been about 8 months since I upgraded the lights, about a year since the new tank. Or 2 weeks I guess since I recently replaced the sandbed from black sand to white, and had to remove everything to get all the old sand out. :p