Terragen seems to have always had better noise reduction in their render engine - probably because they are using a second pass Fast Fourier type noise reduction transform as part of its rendering stack (I'm only guessing on this).  There are several inexpensive photoshop compatible noise reduction post processing tools which can produce exactly the same effect ( I use one called Neat Image).  Terragen can produce some very nice looking terrains, but it's a poor mans Vue IMHO because it doesn't have a high powered Veg solution or sophisticated atmospheric engine like Vue.  I've also heard that TG2 is exrcruciatingly slow.  Also, I wouldn't hold your breath on the Dec 15th release date.  They have been promising TG2 for the past 3 years.