Kn,
from my perspective you are comparing apples to oranges when comparing the T Studio to any of the arrangers. Two almost totally different animals. Different sounds and very different ways in which to approach doing your work between arrangers and workstations. The Studio will definately be more complex to work with and less built in help like styles etc.

About the return policy at GC....they honor that has been my experience with them, 30 day return no problem.

Having owned 3 Korg products and still having the T Rack .... IMO their stuff does alot but it is complicated and don't count on support from them when you can't figure it out either has been my experience. Their manuals to me are written for engineers and programmers.

The best you could do is go to a Korg workstation specific forum and get help there for your Q's.

I think which one you choose between the 3 depends alot on what you do and how you want to do it as well.
Terry