One of the beautiful things about Easton wheels is that a switch from Campagnolo to Shimano or SRAM componentry or vice-versa won't necessitate a new wheel purchase. You could just replace the freehub with one that is compatible with your new gear. Likewise, if you routinely use two different cassette ratios depending on your race courses, you might think about a spare freehub body. It's actually quicker and easier to remove the whole freehub body (cassette and all) with two 5mm hex keys than it would be to fumble with a chainwhip, lockring tool, and wrench to remove and swap cassettes.
The Easton R4 Freehub Body runs on high quality 6902 steel bearings. It has three spring loaded pawls and is compatible with all Easton EC90 and EA90 road wheelsets. It's available in three versions: