Hi! I've got a little story to share.
So I bought this super cheap old Mac Mini 2006/7 (chassis says '06, internals '07). It was fitted with 4GB of RAM (all detected), Core2Duo 1,83Ghz, Intel GMA950 and ran Snow Leopard (EFI already upgraded and showed MacMini2,1). I put Lion onto it in no time. Frankly, I would be perfectly happy with 10.7.5 if only I could get a modern browser and Ulysses running. Unfortunately, that is not the case. So I tried with El Capitan and it managed to boot (even though none of the above methods worked for me; I used another Mac to install and restore) but run into the yet unsolved USB issue. Then Yosemite it had to be.
Again, installed Yosemite on a USB with another Mac, restored that USB to a partition on Mini, patched it with SFOTT and... it booted. USB worked like a charm. Cool. Configured, created an account and... crash. Tried again, got me back to the configuration screen. I went through all of it again (it remembered the account I made before but I still had to create a new one) and this time, miracle!, login screen loaded. Alas, this is the end of good news. As soon as I enter the password and try to login it crashes, every time I try - no miracles this time.
I suspect it must have something to do with GMA950 (cursor is lagging, the screen flashes with grey bars occasionally). Unfortunately I had no luck so far to get OS X Hackers' kexts installed. The .pkg file they provided can't be targeted to any other partition than the current one and I am not learned enough to unravel it, extract what I need and inject it back to the Yosemite drive. (KextsBeast from tonymacx82 couldn't do the targeting either). I will try to do the same trick as with making of the installation drive (install kexts on the USB from another Mac and restore to Mini) but I doubt it will work. After all, to get to the macosExtractor installation stage I need to configure the Yosemite installation and it will then point to a completely different machine. Maybe SFOTT can fix it, I'll keep you posted. If not, then I am back to Lion, I guess. I hope there is still at least one decent browser out there and a markdown-compatible text editor.
All best and good luck to you all!