Please don't take this as trolling, but...
Apart from the hobby/nostalgia factor, is there actually any real reason to use OS4? My reasons for using my last miggies, were some really good old aps, and great old games.
Are there aps for OS4 which can attract a user base? I think it can run UAE, but can it run it as well as Windows on cheap, fast hardware? I presume it would make better use of an underutilised PPC accellerator on a classic miggy, but what would it actually be used for? Can the classic version take full advantage of the old hardware for running old apps?
For my computer usage, I currently find XP to be the most capable OS. It has the apps I need to do my work, and I can buy a copy for about $20 now. I use Xubuntu for other tasks at home. Xubuntu performs pretty well on modest hardware, and can do standard jobs quite well, but there isn't the functionality of my favourite Windows apps.
So I'm left wondering: apart from being kind of cool in its own way, what does OS4 offer at this point? I loved my miggies, but I'm not a fanboy. My really good old Amiga apps have now been superceded by my Windows apps, and I'll probably buy a PS2 or PS3 pretty soon for gaming.