I recently bought a 2008 MBP 4.1 and , after putting on a clean install of Snow Leopard , ran the mavericks download , which it runs happily .
Just out of interest , I tried the Yosemite installation and found that went on just fine . What I didn't like was that Yosemite does not support FCP7 , and although I have FCPX , I don't like it , so I reverted back to mavericks .
I also don't like the iOS8 style appearance of all the icons , and also preferred Mavericks for the classic style icons ( not that appearance on its own would be a factor for choosing or rejecting the OS ) .