From the IT perspective, this is workable and the delays and problems caused are livable. From a teacher's viewpoint, that may or may not be the case. I have two types of teachers at my school and so do you. There are casual users and the power users. The casual users may have some assignments typed, maybe do an occasional PowerPoint project or use the computer for grades.
Power users take full advantage of the computer.
They use multimedia, video and big-screen projectors as part of they daily lessons. While the casual user may be unhappy when the computer is down for six weeks, it isn't the end of the world. For the power users it is, and they will begin to form lynch mobs. They are using the equipment to its fullest, which as a taxpayer and parent I think is a pretty good idea. I talked to one administrator who said that labs were the way to go, run by a para-educator with the least amount of power that would run the systems, minimum RAM, minimum chips.