We had a discussion a while back regarding using flash cards instead of an HD, and I think it was Teho who is using such a method on the A600. From what I have read though there are a few downsides to using a flash card compared to a real HD on the Amiga. Things such as compatibility with some software and games and the transfer speed.

I've always wanted to do a major A1200 to tower conversion project myself, upgrading the system with PPC and PCI/Zorro breakout board, but as time has gone on I now find myself mainly using Amiga software via emulation and leaving the actual hardware behind. Don't get me wrong, I do still love the actual Amiga hardware, but compared to emulation it is now more fiddly to get the variety of software running on the Amiga compared to just changing the settings in emulation.

Maybe if the new PPC Amiga actually reaches production I may once again take a direct interest in building a really good PPC Amiga.