I use beer smith - not sure where you heard about the 'inaccurate for small batch' thing from the other thread. I've used beer smith and now beer smith 2 for years and I personally think it is a very flexible and (relatively) easy program to navigate. I am not IT inclined at all, but once I got my head around the equipment profile stuff I find I can adjust my boil times and efficiencies and what not for different size batches or experiments and usually end up within one or two gravity points. Nothing beats just getting to know your system though...everything else comes after that (for me).
I've used it on Mac Air, Macbook Pro and iMac.