If you read through the forums, the service has been somewhat lacking because it seems to be a 'one man left' software shop that Leviton bought. The original developer left some time ago, then a bunch of (good?) updates came out, afterwards it's gone somewhat dormant. They've narrowed their product offering and refused to give customers what then want (try upgrading from Standard to Pro).
It's sad because Leviton has a lot of potential to do this right, it's a product the industry needs, but they fall very short and it's definitely a tarnish to their name because of it.
As much as I would love to be proved wrong, and see an OS X version, and purchase an upgrade from Std to Pro, I have the distinct feeling I will never see any of my wishes. :(
Best of luck,
Mav