For this use SuPodium
Mac / Windows...same license
Great in exterior renderings
More than user friendly...like twighlight, which hasn`t a Mac version now
Podium starts with the new V2.0 ( beta ) which has also no Mac Version in beta stage, but the actual 1.7 works well on Mac and will be supported further. You won`t loose anything by buying it know, if you want to uprgrade to the new release later.
Informations are by http://www.suplugins.com
Also please take a look here in the forum with the search function. You'll find a lot of information about all the renderengines, including http://forums.sketchucation.com/viewtopic.php?f=81&t=3220.
greetings from the 21th century