question about upgrading from X3 and the subscription Updates.

Will updates be tiered based upon which version of the software you own? forinstance woth the top level get cooler updates than the lower level? I own X3 Producer and looking at the feature specs I dont see why I should pay for platinum when I already own all of the vsts already (unless the vsts included in X3 will be incomparable with the New Sonar which would really piss me off) and all of the versions have the same base software structure. The only way I could see it making sense for Cakewalk is if the higher end version gets more features through the course of the year.

There are a lot of people considering going Professional from Producer instead of to Platinum.  It will be a personal choice.  There are a few features that won't be in Professional (see the comparison chart) but those may not matter to you.
 
However, I think there is an expectation that Platinum members will get better goodies (in the form of content - loops, presets, samples, tutorial videos, etc.) than Professional or Artist.  Depending on whether Cake delivers on that expectation, different decisions may be after year 1.