I am using the Water Floss at the urging of my dental hygienist because of gum issues. So far it's cleaning my teeth and gum area fairly well. The jury is still out though. It's noisy.
The WP-100 is not as big as its counterpart ( I had this one for at least 2 1/2 years before the attachment remained stuck) but it does the job. It is also small enough to sit one a small bathroom countertop.
I have used this type Water Pik for many years. Had to have a replacement because the water tube broke. It was several years old and lasted longer than many plastic items I have had. The Water Pik is excellent for cleaning teeth and helping keep gums healthy.