I love my Whites DFX and have had it a good few years,why do i own one well its well built as other have mentioned,good customer service and many other things as well but the main thing it suits my style of detecting and works well,but i also have other brands as well as i feel that no one brand or specific model does it all in the detecting scene,as a general rule most of the top brand name detector makers make a 'general' all purpose detector then they tend to make specific 'niche' detectors as well this could be for nuggett hunting or diving or what ever.
Someone recently on this forum mentioned that detectors are like a set of golf clubs,you need a putter,driver that type of thing and that i can relate to detecting as trying to use a putter to fire the golfball down to the green from the tee aint going to work is it.
Its nice to have a selection of detectors that you can use,of course that is if you can afford them,this is why the top makers have the general detector that does most things albeit not the best scenario but you can get by with it.
The one thing that i have always said you can own the most expensive detector on the planet but just by doing so does not increase your finds,that is down to the skills of the operator,a cheap detector used by a experianced detectorist will always find much more that a rookie with the most expensive detector going.Its that vital 12'' between the headphones that makes all the differance in detecting its called 'experiance and skill'