Re: No, you don't wish you'd have bought it.
...I particularly relished the idea of putting multiple modern motherboards and drives in the AS/400 case - the size of a half-height filing cabinet - and figuring out uses for its front-panel switches and LED display.
Was planning on doing the same sort of thing myself, except it was a Wang OIS-50 (one of the main boards was dead, and I didn't have a terminal anyway). Then I decided it would probably be too much work or even impossible to mod the case. Later on I saw all the wild and outrageous case mods and installs into anything you could hollow out a mini-ATX sized hole out of, and I realized it would have been dead simple to make an ATX board fit.
Of course, the Mac G5 case, which would *seem* to be an easy mod, is a nightmare in the making (from the videos I've seen on it).