Thanks that's a very useful notes for me. I am in the same situation as you. I have a SB600, and SB800, and I thought originally to buy a YN622TX for the camera, and get a extra flash, and another 3 pcs of YN622N triggers to complete the setup of 3 off camera flash system.
Camera + YN622TX...
Added a free 2m long USB cable for tethered shooting with DIYPhotoBits Camera Control 5.2 (download here)
with this long cable, it is possible to shoot tethered to your laptop and see your image instantly.. good for model shoot and macro shooting.