I don't really like to promote or disparage any particular product, but I am not a fan of adjustable weight knives, for three reasons. One, those weights stick out the sides, and this can really ruin your grip and your ability to handle the knife. Two, those moving parts are just begging to be broken or slip out of place. Three, they're expensive.
I like the look of a pretty knife as much as anyone, but to me performance is always most important with throwing knives because you're endangering yourself if you're missing a lot and knives are bouncing around unpredictably. I think it's best to learn with cheap, dull knives that you don't mind breaking, and then once you know what you're doing, experiment with different kinds of equipment.
That's just my personal preference, though, and if someone is happy throwing adjustable-weight knives, then that's what they should do. The most important things are experimentation and finding out what works for you individually, and, of course, practice!