well Ive used them for nearly two years now,
now some of there advantages, if you use a trolley or backpack or even small van system, they reduce the amount of water used, this is good for several reasons, ie, less stress on your motor carrying less water or as my mate says he gets two days work out of his 500ltr van system, so less water needed to be produced so less waste and lower water bills. i also find a get a better rinse with them also the fine jet is good for bird muck and rinse in of the sills, there are a few other advantages but just takes some thought not negative, they might not suit everyone but they suit many, try it for yourself