I moved my tank with 2 people, 30 gallons with all my gravel in it, minus rocks, about 200lbs. I don't think the tank is any worse for wear, and I have a piece of glass in the corner to create a second level. It survived as well full of gravel, and I'm no pro-siliconer.
I don't think that the base pressure is going to change much at all if it is just gravel in the bottom of the tank. The pressure will be spread evenly over all the bottom glass unless you're doing some heavy duty tilting. With the tank empty the gravel will not move much, and the pressure is all on the strongest part of the tank(the bottom).
My plants would have broken if I'd left them in, and the roots severely damaged just from the shifting gravel. The stems would likely break too since they can't float.
I moved my tank 3/4 full of water with all rocks & stuff across a room the other day and it seemed ok too, no leaks, cracks or scared fish. I didn't tank the tank off the stand though, I just had a friend help me pick up the stand and do a shuffle.