I've used 3 of there racks in the past for 4 years. I had great success with them, raised up my snakes from hatchlings and had my first 3 beautiful clutches all 100% HATCH in 2004.
They work well, but prepared to heat the room there going to be used in, and makesure you plan to keep the room itself at a dedicated 60%-70% humidity.
They are good for dedicated snake rooms, were the whole room must be climate controlled.
They are NO GOOD if you plan to use them in say a room were you sleep.
The need a dedicated snake room period otherwise they WILL NOT WORK well.
The nicest thing about them is that in the summer time you can sometimes open the windows in the room to allow ALL of the snakes some nice fresh air. The open-air system I am sure is good for the animals.