It really helped at Parc to work with real geniuses like Chuck Thacker and Dan Ingalls (and quite a few more). There is a very thin boundary between making the 2nd order work vs getting wiped out by the effort.
Another perspective on this is to think about "not getting caught by dependencies" -- what if there were really good independent module systems -- perhaps aided by hardware -- that allowed both worlds to work together (so one doesn't get buried under "useful patches", etc.)
One of my favorite things to watch at Parc was how well Dan Ingalls was able to bootstrap a new system out of an old one by really using what objects are good for, and especially where the new system was even much better at facilitating the next bootstrap.
I'm not a big Unix fan -- it was too late on the scene for the level of ideas that it had -- but if you take the cultural history it came from, there were several things they tried to do that were admirable -- including really having a tiny kernel and using Unix processes for all systems building (this was a very useful version of "OOP" -- you just couldn't have small objects because of the way processes were implemented). It was quite sad to see how this pretty nice mix and match approach gradually decayed into huge loads and dependencies. Part of this was that the rather good idea of parsing non-command messages in each process -- we used this in the first Smalltalk at Parc -- became much too ad hoc because there was not a strong attempt to intertwine a real language around the message structures (this very same thing happened with http -- just think of what this could have been if anyone had been noticing ...)
What is your preferred technology stack?
I think, usable day-to-day, I'd say you're down to Haiku, MorphOS, Genode, MINIX 3, and/or A2 Bluebottle. Haiku is a BeOS clone. MorphOS is one of last Amiga's that looks pretty awesome. Genode OS is a security-oriented, microkernel architecture that's using UNIX for bootstrapping but doesn't inherently need it. MINIX 3 similarly bootstrapping on NetBSD but adds microkernels, user-mode drivers, and self-healing functions. A2 Bluebottle is most featured version of Oberon OS in safe, GC'd language. Runs fast.
The usability of these and third party software available vary considerably. One recommendation I have across the board is to back up your data with a boot disc onto external media. Do that often. Reason being, any project with few developers + few users + bare metal is going to have issues to resolve that long-term projects will have already knocked out.
BTW, prior to SqueakNOS we implemented this: http://swain.webframe.org/squeak/floppy/ (using Linux and modifying Squeak to work with SVGALib instead of X) in just 900mb inspired in QNX Demo Disk: http://toastytech.com/guis/qnxdemo.html
It's neat that it was the thing that inspired one of your Squeak projects. Is SqueakNOS usable day-to-day in any console desktop or server appliance context? Key stuff reliable yet?
https://www.youtube.com/watch?v=NdSD07U5uBs 'Power of simplicity'
Does that mean the messages should have been part of a coherent protocol or spec? That there should have been some thought behind how messages compose into new messages?