The A900 has several useful functions: mirror lock up, auto bracketing, and the remote commander.
Can they be used in combination?
The same (drive) menu is used to select between these three functions. Ideally one would be able to use them together.
The remote commander does away with the need for any corded remote. Use that together with, say, continuous autobracket when the A900 is on a tripod and hey presto, an HDR redy combination taken with minimum effort. Or maybe select mirror up and use the remote commander for reduced vibration.