TOPIC: Updating from old J1.5 to 2.5 or 3.0?

Hi there, we have a site from a couple of years ago still running Joomla 1.5 that I want to update to get current. It's a stand alone install in a sub-folder of our main site (which is not joomla at the moment) & it's just running DTReg, with no user sign up or community builder etc etc.

Question is - is Joomla 3.0 & DTReg 3.0.1 ready for a live site? Or still a work in progress?
I've been out of the game for a while & just wondering if 2.5 might be better as hopefully all the bugs will be ironed out by now... from both Joomla & DTH

Also I realise that as our original purchase was 2 years ago, we'd need to buy again for the current J2.5 version.

Thanks,
Hez.