I have installed them and like them. One of my wife's Q-tanks are made of one. It's a great tank for the size. I'm not sure I get the "too expensive" concept?
First of all a liner pond done properly is labor intensive. It also has a short life expectancy when compared to the preform depending on the care of installation, then you get to do it all over again. William's preform will way outlast any liner pond of it's size and you virtually can't damage it. Liner is relatively delicate.
If your time is worth much at all the preform pond for that size is a bargain in shape, quality and durability.
