Well... as for H2O and a recent version of Cubase on OSX, I suppose you shouldn't hold your breath, mate. According to the nfo on their last SX for Win, SX3 took them thousands of hours and they stated it would be their last release.
I'm an old Cubaser (since 1990) and I currently run CB4 (legit of course

) on a hack and a MacBook. I can also run SX3 with the same dongle.
As I don't have the time, the patience and the geekdom to take all the Windows hassles I'm quite happy with this OSX setup, even if there are more AU plugins than VST that work properly. Anyway, it was the most rewarding $800 I ever spent on software so far.
Logic Express is...errr... okay... but Cubase leaves it far behind in many fields. Not a fair comparison anyway.
I can't speak for Logic Pro but I reckon it's a bit pricey for what the specs have to offer.