Disturbing the sand a bit while you do water changes can prevent the release of toxic and noxious bubbles of nitrogen from fish waste that may form over time but your aquarium already looks so clean and beautiful, you don't really need to worry about such a minute detail...
It you're in Cali, make sure that beaut' is strapped/fastened to the wall in case of an earthquake...I'd invest in a power generator too!!!
Great aquascaping, you could work for the aquarium in Atlanta, its that good!!!
If you invested in a dimmer switch, I think your aquarium would look even more expensive and world class...the circadian rythm of the fish would also probably benefit from such efforts to recreate nature...if I were you I'd do it...might as well...after you put in such effort into making such a spectacular display tank!!!