I've been quietly reading this thread for a while, and I must say that this is one of the most interesting and promising classic Amiga projects I've seen for a while.
The original Minimig alone is quite interesting and fun to play with every now and then, but if we introduce AGA, more RAM and possibly even more features ('060, hdd and ethernet was mentioned) then this would definitely reach the level of a computer that I could use every day.
Also, MiniITX form factor would be absolutely perfect. No reason to re-invent the wheels with custom cases, let's use what's available.
Good work, keep it up!