If easy cab movement is important to you then I have a couple of suggestions.
#1 Build for low weight, rather than easy dissasembly. That means use plywood rather than particle or MDF, and don't do any interior framing other than the standard 1x1s where the sides meet the front.
#2 Do not make your basic cabinet more than 27" wide or 27" deep. 27" fits through even those narrow 28" doorways (you might have to take the door off the frame, but it will fit). Make sure that your cabinet makes that magic 27" number in either width or depth. Otherwise you WILL eventually encounter a situation where you can't move the cabinet somewhere. You don't have to beat that number in both width AND depth, just beat it in one of them. One of my games (Sprint 2) is like 3 feet wide, but it isn't that deep, so I can still move it around easily.
#3. If your control panel is wider than your basic cabinet, then make it easily removable. This helps out in both the area of weight, and it makes things less awkward.
#4. Finally, if weight is still going to be an issue, then make your monitor easily removable. I know from experience that even a fully loaded plywood cabinet with the monitor removed is an EASY move job for two guys, even up and down awkward stair sets.
Making your basic cabinet multi-piece ins't really the answer, and a basic plywood cabinet really isn't that heavy. To give some easy furniture comparisons. A full standard plywood cabinet with the monitor out is lighter than most couches, and closer to the weight of a larger dresser with no drawers in it.