The Cubase demo is now online and
available here. The Cubase Pro demo requires an e-licenser dongle (mad). If you don't already have one, you can demo Cubase Elements, although bear in mind it's very limited in comparison to the Pro version. You can see a comparison between the
different versions here. (Elements trial download is just under 6GB)
There was a live
Q & A video session yesterday for Sonar users thinking of moving to Cubase. You can
watch that here. It's well worth watching this video!
Other info I have found that you may find useful is;
In the EU/UK you can buy the crossgrade from the Steinberg website. Only the boxed version can be ordered with or without the e-licenser.
In the US you can buy the crossgrade from Sweetwater. This is a download version and you will need to buy an e-licenser dongle separately.
In other countries, you can buy from a local authorized Yamaha dealer. You can find your
international distributor here.
I was able to register on their website and the forum without being a customer. So you can post questions on the forum, but I think they moderate your first forum post before it goes up.
I have been in touch with support via the website to ask some questions and they replied promptly.