Well, a bit OT, and yet not, I have a Tornado (TW's eGo) and it was my first PV. The reason the cone improves draw on THAT device is specific to that device with a 510 atty on it. This particular combo, sans cone, allows too much airflow. The groves in the connector are deep, combine with the airflow holes on the atty and you get a lot of airflow. Put the cone on and it forces the airflow to only come down thru the tiny gap between the upper cone edge and the upper edge of the atty thereby restricting the airflow and improving it.
However, I sometimes use an LR 306 on my tornado batt sans cone, as that atty is too short to reach thru the cone. while the 306 has the same threads as 510 atty, the airflow is somehow different and the draw is awesome even without the cone.
All of my devices are native 510 and I use adapters for 901 and 801 attys. The adapters have adjustable airflow. 510 attys on my GLV need no airflow adjustment but can be slightly adjusted as the connection is strong enough to permit you to back-off or tighten the atty on the connector (changes airflow to some extent).
I remain very enthusiastic about a glass drip tip and possible cart. However, conceptually, I still have concerns about price and practicality (especially cleaning - some juices even a couple of drops can contaminate a new flavor if not cleaned out thoroughly). But, I am enthusiastic about the idea and remain very open - so sign me up for one!