I have both there dual float valve and there two solenoids. They are amazing! 2 years, no floods, no worries, keeps my tanks at the right level everytime, they are built with excellent craftsmen ship and they are affordable.
If you were to build one yourself, like I was about to, it would cost you roughly the same amount as what they charge.
I would definitely buy the dual float valve over the single float valve, it's always nice to have a backup incase the first doesn't shut off.
5/5.