Should I upgrade iMac mid 2007 4GB ram, 2ghz, 250gb HD (no SSD) from Snow Leopard to Yosemite? I tried searching for threads about this, but most people just discuss the idea. Curious to know if anyone has done this, if there is a better speed performance/better stability or is it better to just stick to Snow Leopard. Interested to hear what you guys think, thanks.