Cubase supports 32 bit recording but this is mainly dealing the way that the programs stores the file and uses the internal headroom. There are no audio devices that support more than 24 bit recording. My advice to most people is to not get caught up in bitrates. As long as you record in 24 bits over 16 bits and make sure that your plugins do not operate at any less than a 24 bit bitrate then you're fine. Your program, plugins, etc... will likely work at different bitrates internally.
On topic, I am a Cubase SX user. I'm looking at a Pro tools system only to use it as a way to port pro tools sessions to Cubase sessions when needed or to not deal with the conversion in the first place. My main workstation is still going to be Cubase.
Sonar has a nice vocal manupulation plugin coming out with Sonar 5, that looks interesting also. I don't like the Sonar workflow but their plugin looks interesting. It's close to what Melodyne is except that it's integrated, which is the plus.
Cubase's audio engine is also more accurate than that of the Pro Tools engine. This has been proven with testing the way that both programs add up numbers.