Looking into this a little more, I think the new Wood S H, S M and S L are the new S design whereas the Ebony H/L/TR are an older design. So, I think there is more than just a wood change between the Ebony and Wood lines. But is hard to figure out the exact details.
"Albert Lukaschek of Benz Micro and Garth Leerer of Musical Surroundings announce a new series of phono cartridges, the S Class. Led by the new flagship LP S cartridge, introducing the SLR Gullwing and joined by new versions of the Wood Body, Glider and ACE cartridges, the S Class furthers the performance, selection and value of the Benz Micro line."
More details here -
http://www.musicalsurroundings.com/benz.html
"Albert Lukaschek of Benz Micro and Garth Leerer of Musical Surroundings announce a new series of phono cartridges, the S Class. Led by the new flagship LP S cartridge, introducing the SLR Gullwing and joined by new versions of the Wood Body, Glider and ACE cartridges, the S Class furthers the performance, selection and value of the Benz Micro line."
More details here -
http://www.musicalsurroundings.com/benz.html