Well, I just got my copy of Cubase 5.
I got say it looks like it is gonna blow SX3 away! It opened up my corrupted project no problem (see other thread in this forum), it looks fantastic, you can change the order of plugins (a stupid easy feature SX3 lacked), and it lets me run SX3 off the new dongle! (I sold my copy and dongle from SX3)
Also, all my plugins and all project setting were picked up by Cubase 5. I read on the internet, that all my routings would have to be reset, and I have a pretty complicated set-up. I wasn't looking forward to that! No problems though.....
I'll update again after I use it for a bit. I really want to try the VariAudio feature. It looks like it's pretty user friendly.