Played around with a newly acquired Late 2009 Mini today. It is a 2.26ghz model and it came with a 160 GB HDD with Snow Leopard installed and 2 GB of RAM. I decided to swap my SSD and 8 GB of RAM from my early 2009 Mini into the late 2009 and put the late '09's HDD and 2 GB of RAM into the early '09. Haven't decided exactly what I will do with the early '09 now. Probably make it a Leopard or Snow Leopard box, or if I upgrade it again, maybe Mavericks.
Since the late '09 has a faster CPU, I decided to try out the patched version of Big Sur. While I do prefer earlier versions of macOS, I just couldn't resist trying out Big Sur on here. I replaced the Snow Leopard that was on my SSD with Mojave first because I figured a newer OS was needed to run the OpenCore program and download Big Sur. In hindsight I should have used High Sierra or installed Mojave on an HFS+ partition instead because the APFS boot loader from Mojave interfered with me being able to get into startup manager. That and the 2009 minis weird issue of USB devices not being recognized after a reboot, requiring one to unplug and plug back in the USB cable(s) again, also affected my ability to get into startup manager. So it's hard to say whether the USB issue or the APFS bootloader was to blame. Big Sur without graphics acceleration is awful, things like setting the time zone during setup became a struggle. Once graphics acceleration is enabled thanks to post-install patches, the experience of running Big Sur is not bad. It's not my favorite macOS, but so far it works. It's cool to be able to run Apple's latest macOS on a Mac that's over a decade old.
I'm still able to dual boot with Linux as well. After reinstalling rEFInd, I am able to boot into Linux by selecting EFI from OpenCore, which takes me to rEFInd where I can boot into Linux.
Since the late '09 has a faster CPU, I decided to try out the patched version of Big Sur. While I do prefer earlier versions of macOS, I just couldn't resist trying out Big Sur on here. I replaced the Snow Leopard that was on my SSD with Mojave first because I figured a newer OS was needed to run the OpenCore program and download Big Sur. In hindsight I should have used High Sierra or installed Mojave on an HFS+ partition instead because the APFS boot loader from Mojave interfered with me being able to get into startup manager. That and the 2009 minis weird issue of USB devices not being recognized after a reboot, requiring one to unplug and plug back in the USB cable(s) again, also affected my ability to get into startup manager. So it's hard to say whether the USB issue or the APFS bootloader was to blame. Big Sur without graphics acceleration is awful, things like setting the time zone during setup became a struggle. Once graphics acceleration is enabled thanks to post-install patches, the experience of running Big Sur is not bad. It's not my favorite macOS, but so far it works. It's cool to be able to run Apple's latest macOS on a Mac that's over a decade old.
I'm still able to dual boot with Linux as well. After reinstalling rEFInd, I am able to boot into Linux by selecting EFI from OpenCore, which takes me to rEFInd where I can boot into Linux.