Hi
I also would like to tell that decoupling the UI elements from the Implementation of the core should be a standard practice. In that, Tellurium is nothing new.
WebDriver for example has his PageFactory ( http://code.google.com/p/selenium/wiki/PageFactory ).
So based on that Tellurium is really nothing new. Alas if your framework is robust enough to uphold long endeavors and can stand the iron teeth of time then it really is only a questions of 'like' which one you use.
Your framework should be good enough no matter the technology wrapped around it or in it for that matter.
Gergely.