I have the Citation HVLP system. Very nice, fresh air, and comes with a top of the line gun. Mine's done three planes so far and a lot of spraying. My only regret is I think the gravity fed gun might have been a better choice. I got the bottom feeder (qt. size). It worked really well, but sometimes gets in the way when shooting flat surfaces. The trade off is the smaller cup on the gravity feeder.
The nice thing about the AXIS and Citation systems is the clean, dry, and oil free air for the gun and the cool fresh air for you. I was never uncomfortable, even on hot days. The units are very lightweight and compact in size.
Also, I liked using a half mask with the better cloth hood. They have a Tyvex hood, but it doesn't hold up well. Get a bunch of lense protectors to keep the "window" clean. The hood allows you to more loosely fit the mask. The positive pressure under the hood keeps the fumes out, so having a tight seal on the mask isn't necessary and being a little loose is more comfy.
Roberta