Sprung is a FAR better thing to advertise... but most people don't know the finer nuances of the carpenters language and so saying "floating" does just as good a job. And if they are "flung" then floating is quite appropriate!
Looking into flooring system, DanceFlex is often advertised, since it is used on DWTS. They say it is "floating" and is installed as a clip lock system, but is their quality any better than buying your own pre-finished floor with foam subfloor?
http:// w w w .dancevision.com/store/DF/
With a sprung floor, I take it this is a more permanent structure versus a removable floor system?
I wouldn't say a sprung floor is any more permanent, just more involved in installation. You could probably take up both kinds of floor to move them to another location if you wanted to.
DV says their floor is floating, which only means that it isn't anchored to anything; just laying on top of the subfloor (whether or not there are any other layers between it and the subfloor). As far as quality, it's hard to say. They claim their floor is hardwood, and if it is solid wood, that is much better than the prefinished engineered floors, which can feel a little hard compared to real wood.
A sprung floor—shockingly—has spring to it, to help give you a little rebound when you dance/walk on it, which helps preserve your joints from getting a pounding. The spring is provided by the rubber or neoprene pads and the battens which underlay the wearing surface. The typical floating floor will also have some give, but there is only so much give a thin layer of foam can have.