I've skied both the Supershape Magnum KERS and the liquidmetal version the KERS replaced. I liked them both, but I never had a chance to compare them side by side on the same day, so I can't say whether I would notice a difference. OTOH it seems perfectly plausible to me that you could use electronics to make the ski damper and/or stiffer to bending, and then less damp and/or less stiff when unbending (or vice versa). That's a more sophisticated use of piezio-electronics than the old K2 system, which just added damping.
Whether those systems are allowed on WC depends on the definition of energy storage device. The ski KERS is a control system more than an energy recovery system like the KERS used in Formula 1. OTOH just because it's on the retail ski doesn't mean it's on the WC ski. There's really not much to argue about. You can't really isolate one part of a ski's construction, you either like the ski or you don't. I like the KERS ski.