The Works struts are designed to work with the stock springs. The Fox struts are designed to work with the dual rate HSP springs. Basically the Works struts give a more progresssive dampening (stiffer dampening as the suspension collapses) as opposed to the Fox struts which are a straight dampening rate. They use the HSP dual rate springs to give the progressive dampening.

I had a pair of HSP springs and Works struts on my Sport. The ride was extremely plush in the beginning of the travel and stiffend up some what towards the last part. I never had a problem bottoming, but then I never did a lot of jumping on it. I tried a MX course on my Sport with the Works struts and Stock springs and the front end NEVER bottomed. Even when I landed verticle on a table top (front wheels high)