I put 7.6.1 on every machine that can handle it. It's my baseline OS for most Quadras, Nubus Powermacs and some PCI Powermacs. The problem is that most machines that can handle 7.6.1 can also handle 8.1 so unless there is a severe memory limitation or something else that can't be overcome, I would prefer to have 8.1 on that machine and many of my machines are also beefy enough to run 8.6 or 9. Any Mac I have that is incapable of running 7.6.1 also has problems with any version of 7.5 so I have to stay with 7.1 or lower on those Macs.