I need help in choosing a refurbished Mac Pro 5,1 sporting either the 2.4Ghz 4 core x 2 or a single 3.33Ghz 6 core. Both machines are identical otherwise (ATI Radeon 5770, 16GB RAM) and in price. Im not a power user, but need the expandability offered by the Mac Pro line. What would your recommendation be? Some say the higher frequency of the 6 core is better - but in day to day use in El Capitan would one even feel it? Confused!