Like Washington said, the rest looses contact from the arrow after about three inches of travel. This reduces any ill effects from you torquing the bow since the rest isn't able to move the arrow around before it leaves the string.

For fletching contact it is true that you can align your vanes or feathers to pass through the prongs of the rest but you are very limited in how much offset of helical you can put into your fletching and still have no fletching contact. Many people like to use hard 11 degree helical and that will not pass through a TM style rest with out contacting the prongs.

IMO there is no reason not to use a drop away except if you use a biscuit type rest.