Matcham,
It appears the new version is 64 bit for Windows and you have to register as a user to see download now, but there is no MAC version at the moment, though they are working on it. (Go to their site and you will see.)
I too have Ozone, and the level meters are useful, but they are relative loudness and peak levels. That is different than dynamic range and that is why I love this meter.
Ozone will tell you how loud you are and you can see spectrum graphs, but you can't get a number for the dynamic range. I find those simple numbers to be very useful. If you have a dynamic range in the 11 to 12 range you know you have a Cat Stevens, Pat Metheny or Steely Dan mix, it will be crisp and resonant.
If you have a dynamic range of 3 you will be sounding like the Clash through busted speakers. You probably have over compressed the heck out of everything and need to go back to the drawing board.
Everyone is so focused on volume these days they have completely forgotten about dynamic range--that is the wood of the guitar, the bell like sound of piano high keys, the skin on the drum. You know, the good stuff.