I have owned a lot of mapping programs over the years but the vast majority of them were Windows based starting with Hanta Yo, Delorme Topo Quads, Topo!, Nat Geo Topo!, Garmin Topo 2008, Topo USA versions, 7, 8, Mac GPS Pro, and currently Topo USA 9. I still keep a Windows machine in the basement to run Topo USA 9 and that is what I currently using but I plan on putting Parallels or Fusion on my Mac running Topo USA 10 from Delorme when I redo my MacBook Pro, which is what most of the mapping software companies recommend using or Boot Camp, but then you have to reboot to get into Windows. I haven't upgraded yet I was holding out that they would port it over or make a Mac version but so far no such luck in that department.
Roger