Yeah, I just paid for the map pass from mytopo. I like it pretty well, can print custom maps with framed UTM/lat/long/ scale info, just a little sluggish. I love HIllmap.com but haven't had much luck printing. So I started looking elsewhere but have not been able to find any reasonable GIS software for mac. TerraGo toolbar is a plugin for adobe acrobat/ reader which should allow manipulation of USGS pdf topos but it's only available for, you guessed it, Windows.
I wanted to try out topo fusion, I even thought about using parallels or the like so I could run it on a virtual windows machine but that's a hassle.