I love those machines. I can't help it. They were the best part of my day back in high school (this was around 1994/95), because I just loved futzing around on them. Loved the look of them too, from the core system to the monitor and keyboard. Classic all the way.
The model M keyboards... those are something special, never had a better keyboard than those, I've got two of them bit loud but easy to clean, also useful to clobber someone with... they've got a thick steel plate in the back.
I managed to get a hold of an IBM keyboard a few months ago for my mom. She has trouble typing on these newer keyboards, and so I went about finding something more fitting. As you mentioned, they have a steel plate in the back, so they're heavy, the keys spring back quickly and they make a satisfying clickety clack noise, which she loves. She wouldn't trade that keyboard for a brand new modern one if you begged her (not that I've tried

).
I don't have the space to have the collection you do,
Santaman, but I wish I did. I love old computers. I've made plans to visit the official computer museum in California, should I ever get out that way. Some people see these antiquated systems as curiosities, but they're much more than that. At one time, these old computers were the technological marvels of their day, and they deserve respect (except for any and every Packard Bell system which can DIAF).