With ebays return policy I would buy a OEM without hesitation. just buy from a reputable seller. If it doesn't work, your not out anything. just your time.
as for calctric - its all imported Chinese electrical components. I work on atv's daily. you quickly find out what lasts and what doesn't. They use a smaller gauge wire on most, along with cheap connectors. Just not quality.
If your wheeler doesn't trek far out in the backcountry and isn't relied on - I would say give caltric a try.
Where I ride I cannot count on a Chinese part. So its always OEM electrical components or ricky components if OEM isn't attainable.