MRC,
It's true that the springs wear out after heavy usage, but they come with a rubber protective cover. Many people also wrap them in fabric tape to further protect it from the elements.
I find myself at High Rock (Overlooks Smithsburg) quite often on weekends, and sometimes offer demos/ tryouts of the Powerisers there. Not sure how close that is for you but if you email me I could give you a call next time I'm there for demo lessons. We could also watch people launch in hang gliders and flying around, if there's wind from the NW around 10mph.
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David
DC Power Stilts