One thing that I'd like to add to this discussion that I think haven't been touched yet....
The Creamware system is much more of compositional framework than a bunch of DSP plugs. No doubt the UAD and Powercore have quality behind them, but if you are interested in real composition and want to learn more about how sound works, have total control over sonic manipulation and simply have access to about 70 synths, 100+ FX, and numerous toys, you'll definately appreciate the Creamware environment.
I DLed all of Hummel's synths (
http://www.track0.com/wavelength/shareware.html) when he first made the batch shareware, and didn't use them at first, but as I began exploring them, I began to really dig into all the 3rd party stuff floating around and there are some really fantastic tools out there that are free.
The 'Saturn' synth is a classic, Hummel's synths, Neutron's plugs (though he's on plug-making sebatical at his current job), and the new Adern teams contributions are all fantastic. These types of choices and dynamic sounds are a product of being able to operate outside of the paradigm of what the producing company has in mind for it's next releases. I'm pretty sure Powercore is a closed system.
Though Creamware is not exactly an open book with it's 3rd party developers, there is enough communication and rabid followers/designers interested that when one group slows down, some new one pops up with fantastic releases. You will definately get much more return on your investment going with a community of developers, fans, and audiophiles, than just dealing with TC. I've learned more about audio from this forum and playing with my studio-in-a-box (which in my opinion is a title that sells the CW platform short) than from school or books, or even talking to professionals.
This is a system that will flex itself in whatever direction you find yourself working, composing, playing.
Just make sure you have a good motherboard before taking the plunge. You will hate life if you have a cheap board. A search for 'motherboard' or 'mobo' will display endless threads for you to look through.
Hopefully that gives you some more understanding about what the platform is outside of just the raw plugs.
Sam