I agree. Tiger is FAST on this machine. I’m curious about just how quick it would boot with an SSD - maybe 20 seconds? The only drawback I have found with Tiger is it doesn’t handle the trackpad responsiveness quite the same as 10.5+, but it’s only very minor. I think I understand... The polycarbonate 2006-2009 MacBooks are prone to cracking, but you’d say they are pretty solid electronically? I have been very impressed with the late 2009-2010 white poly unibody with the 9400m. I salvaged one with a faulty display for free back in 2015, replaced the display assembly and it has been my wife’s main machine since. This design is tough as nails and the big rubber boot was great - even if it did attract a bit of grime. It also officially runs High Sierra. There was a person who claimed to successfully replace the MB1,1 logic board for a MB5,2 board in a blackbook here. I imagine @dosdude1 could probably get an even faster CPU in there. How about a 3Ghz BlackBook?