I looked seriously recently at the LSG grills when ordering my LSG IVC smoker. After speaking with Chris, I ended up going with the Assassin.
I LOVED the LSG, but appreciated the fact the Assassin would allow me to more easily do two zone cooking or smoking as it controls the airflow. The LSG does not as the vent runs across the entire rear and cannot be controlled.
What I found surprising, is how much I use my 26" Weber Kettle even with the LSG smoker and Assassin Grill. As much as I love the Assassin, it take a bit more effort than the Kettle and sometimes after a long work day, I want the ease of the Kettle. I also like that the Kettle gets the charcoal much closer to the grate than either the Assassin or the LSG. Per Jeff at Assassin you can not run the charcoal on the higher rack on the Assassin to get the grate closer to the meat.